diff --git a/app/controllers/api/projects_controller.rb b/app/controllers/api/projects_controller.rb
index edba3986a..52ab64663 100644
--- a/app/controllers/api/projects_controller.rb
+++ b/app/controllers/api/projects_controller.rb
@@ -63,7 +63,7 @@ def show_context
     private
 
     def set_auth_cookie_for_scratch
-      return unless @project.project_type == Project::Types::CODE_EDITOR_SCRATCH
+      return unless @project.scratch_project?
       return unless Flipper.enabled?(:cat_mode, school)
 
       cookies[:scratch_auth] = {
diff --git a/app/controllers/api/scratch/projects_controller.rb b/app/controllers/api/scratch/projects_controller.rb
index bc9a1bcc0..772056ee1 100644
--- a/app/controllers/api/scratch/projects_controller.rb
+++ b/app/controllers/api/scratch/projects_controller.rb
@@ -14,12 +14,30 @@ def show
       end
 
       def create
-        render json: { status: 'ok', 'content-name': 'new-project-id' }, status: :ok
+        original_project = load_original_project(source_project_identifier)
+        return render json: { error: I18n.t('errors.admin.unauthorized') }, status: :unauthorized unless current_ability.can?(:show, original_project)
+
+        remix_params = create_params
+        return render json: { error: I18n.t('errors.project.remixing.invalid_params') }, status: :bad_request if remix_params.dig(:scratch_component, :content).blank?
+
+        remix_origin = request.origin || request.referer
+
+        result = Project::CreateRemix.call(
+          params: remix_params,
+          user_id: current_user.id,
+          original_project:,
+          remix_origin:
+        )
+
+        if result.success?
+          render json: { status: 'ok', 'content-name': result[:project].identifier }, status: :ok
+        else
+          render json: { error: result[:error] }, status: :bad_request
+        end
       end
 
       def update
-        scratch_content = params.permit!.slice(:meta, :targets, :monitors, :extensions)
-        @project.scratch_component&.content = scratch_content.to_unsafe_h
+        @project.scratch_component&.content = scratch_content_params
         @project.save!
         render json: { status: 'ok' }, status: :ok
       end
@@ -27,9 +45,34 @@ def update
       private
 
       def ensure_create_is_a_remix
-        return if params[:is_remix] == '1'
+        return if params[:is_remix] == '1' && params[:original_id].present?
+
+        render json: { error: I18n.t('errors.project.remixing.only_existing_allowed') }, status: :forbidden
+      end
+
+      def source_project_identifier
+        params[:original_id]
+      end
+
+      def create_params
+        {
+          identifier: source_project_identifier,
+          scratch_component: { content: scratch_content_params }
+        }
+      end
+
+      def load_original_project(identifier)
+        project_loader = ProjectLoader.new(identifier, [params[:locale]])
+        original_project = project_loader.load
+
+        raise ActiveRecord::RecordNotFound, I18n.t('errors.project.not_found') unless original_project
+        raise ActiveRecord::RecordNotFound, I18n.t('errors.project.not_found') unless original_project.scratch_project?
+
+        original_project
+      end
 
-        render json: { error: 'Only remixing existing projects is allowed' }, status: :forbidden
+      def scratch_content_params
+        params.slice(:meta, :targets, :monitors, :extensions).to_unsafe_h
       end
     end
   end
diff --git a/app/models/project.rb b/app/models/project.rb
index 1cfa3faab..c28650ffb 100644
--- a/app/models/project.rb
+++ b/app/models/project.rb
@@ -82,6 +82,10 @@ def media
     images + videos + audio
   end
 
+  def scratch_project?
+    project_type == Types::CODE_EDITOR_SCRATCH
+  end
+
   private
 
   def check_unique_not_null
diff --git a/config/locales/en.yml b/config/locales/en.yml
index 5cef4714e..ce3d9c076 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -4,6 +4,7 @@ en:
       unauthorized: "Not authorized."
       csv_file_required: "A CSV file is required."
     project:
+      not_found: "Project not found"
       editing:
         delete_default_component: "Cannot delete default file"
         change_default_name: "Cannot amend default file name"
@@ -12,6 +13,7 @@ en:
       remixing:
         invalid_params: "Invalid parameters"
         cannot_save: "Cannot create project remix"
+        only_existing_allowed: "Only remixing existing projects is allowed"
   validations:
     school:
       website: "must be a valid URL"
diff --git a/lib/concepts/project/operations/create_remix.rb b/lib/concepts/project/operations/create_remix.rb
index ef42defc3..81f70714b 100644
--- a/lib/concepts/project/operations/create_remix.rb
+++ b/lib/concepts/project/operations/create_remix.rb
@@ -23,7 +23,11 @@ def validate_params(response, params, user_id, original_project, remix_origin)
       end
 
       def remix_project(response, params, user_id, original_project, remix_origin)
-        response[:project] = create_remix(original_project, params, user_id, remix_origin)
+        response[:project] = if original_project.scratch_project?
+                               create_scratch_remix(original_project, params, user_id, remix_origin)
+                             else
+                               create_remix(original_project, params, user_id, remix_origin)
+                             end
         response[:project].save!
         response
       end
@@ -50,11 +54,19 @@ def create_remix(original_project, params, user_id, remix_origin)
         remix
       end
 
+      def create_scratch_remix(original_project, params, user_id, remix_origin)
+        remix = format_project(original_project, params, user_id, remix_origin)
+        scratch_component = params.fetch(:scratch_component)
+        remix.build_scratch_component(content: scratch_component[:content])
+
+        remix
+      end
+
       def format_project(original_project, params, user_id, remix_origin)
         original_project.dup.tap do |proj|
           proj.identifier = PhraseIdentifier.generate
           proj.locale = nil
-          proj.name = params[:name]
+          proj.name = params[:name] || original_project.name
           proj.user_id = user_id
           proj.remixed_from_id = original_project.id
           proj.remix_origin = remix_origin
diff --git a/spec/concepts/project/create_remix_spec.rb b/spec/concepts/project/create_remix_spec.rb
index 3978c47bc..50cc4a170 100644
--- a/spec/concepts/project/create_remix_spec.rb
+++ b/spec/concepts/project/create_remix_spec.rb
@@ -129,6 +129,49 @@
       end
     end
 
+    context 'when the original project has Scratch content' do
+      let!(:original_project) do
+        create(:project, project_type: Project::Types::CODE_EDITOR_SCRATCH, locale: nil)
+      end
+      let(:original_scratch_project) do
+        {
+          meta: { semver: '3.0.0' },
+          targets: ['original target'],
+          monitors: [],
+          extensions: []
+        }
+      end
+
+      before do
+        create(:scratch_component, project: original_project, content: original_scratch_project)
+      end
+
+      context 'when new Scratch content is provided' do
+        let(:remixed_scratch_project) do
+          {
+            meta: { semver: '3.0.0' },
+            targets: ['remixed target'],
+            monitors: [],
+            extensions: ['pen']
+          }
+        end
+        let(:remix_params) do
+          {
+            name: 'My remixed project',
+            identifier: original_project.identifier,
+            scratch_component: {
+              content: remixed_scratch_project
+            }
+          }
+        end
+
+        it 'uses the supplied Scratch content' do
+          expect(create_remix[:project].scratch_component.content.to_h)
+            .to eq(remixed_scratch_project.deep_stringify_keys)
+        end
+      end
+    end
+
     context 'when user_id is not present' do
       let(:user_id) { nil }
       let(:params) { { project_id: original_project.identifier } }
diff --git a/spec/features/scratch/creating_a_scratch_project_spec.rb b/spec/features/scratch/creating_a_scratch_project_spec.rb
index a06446997..d3e17f6ce 100644
--- a/spec/features/scratch/creating_a_scratch_project_spec.rb
+++ b/spec/features/scratch/creating_a_scratch_project_spec.rb
@@ -5,16 +5,52 @@
 RSpec.describe 'Creating a Scratch project (remixing)', type: :request do
   let(:school) { create(:school) }
   let(:teacher) { create(:teacher, school:) }
-  let(:cookie_headers) { { 'Cookie' => "scratch_auth=#{UserProfileMock::TOKEN}" } }
-  let(:params) { { original_id: 'original-project-id', project: { targets: [] }, is_remix: '1' } }
+  let(:headers) do
+    {
+      'Cookie' => "scratch_auth=#{UserProfileMock::TOKEN}",
+      'Origin' => 'editor.com'
+    }
+  end
+  let(:request_query) { { original_id: original_project.identifier, is_remix: '1' } }
+  let(:scratch_project) do
+    {
+      meta: { semver: '3.0.0' },
+      targets: ['updated target'],
+      monitors: [],
+      extensions: ['pen']
+    }
+  end
+  let(:lesson) { create(:lesson, school:, user_id: teacher.id) }
+  let(:original_project) do
+    create(
+      :project,
+      school:,
+      lesson:,
+      user_id: teacher.id,
+      project_type: Project::Types::CODE_EDITOR_SCRATCH,
+      locale: nil
+    )
+  end
 
   before do
+    mock_phrase_generation('new-project-id')
+    create(:scratch_component, project: original_project)
+
     Flipper.disable :cat_mode
     Flipper.disable_actor :cat_mode, school
   end
 
+  def make_request(query: request_query, request_headers: headers, request_params: scratch_project)
+    post(
+      "/api/scratch/projects?#{Rack::Utils.build_query(query)}",
+      params: request_params,
+      headers: request_headers,
+      as: :json
+    )
+  end
+
   it 'responds 401 Unauthorized when no cookie is provided' do
-    post '/api/scratch/projects', params: params
+    make_request(request_headers: {})
 
     expect(response).to have_http_status(:unauthorized)
   end
@@ -22,30 +58,72 @@
   it 'responds 404 Not Found when cat_mode is not enabled' do
     authenticated_in_hydra_as(teacher)
 
-    post '/api/scratch/projects', params: params, headers: cookie_headers
+    make_request
 
     expect(response).to have_http_status(:not_found)
   end
 
-  it 'responds 403 Forbidden when not remixing' do
-    authenticated_in_hydra_as(teacher)
-    Flipper.enable_actor :cat_mode, school
+  context 'when authenticated and cat_mode is enabled' do
+    before do
+      authenticated_in_hydra_as(teacher)
+      Flipper.enable_actor :cat_mode, school
+    end
 
-    post '/api/scratch/projects', params: params.merge(is_remix: '0'), headers: cookie_headers
+    it 'responds 403 Forbidden when not remixing' do
+      make_request(query: request_query.merge(is_remix: '0'))
 
-    expect(response).to have_http_status(:forbidden)
-  end
+      expect(response).to have_http_status(:forbidden)
+    end
 
-  it 'return new project id when cat_mode is enabled and a cookie is provided' do
-    authenticated_in_hydra_as(teacher)
-    Flipper.enable_actor :cat_mode, school
+    it 'responds 403 Forbidden when original_id is missing' do
+      make_request(query: { is_remix: '1' })
+
+      expect(response).to have_http_status(:forbidden)
+    end
+
+    it 'responds 404 Not Found when original project does not exist' do
+      make_request(query: { original_id: 'no-such-project', is_remix: '1' })
+
+      expect(response).to have_http_status(:not_found)
+    end
+
+    it 'responds 404 Not Found when the original project is not a Scratch project' do
+      non_scratch_project = create(:project, school:, lesson:, user_id: teacher.id, locale: nil)
+
+      make_request(query: { original_id: non_scratch_project.identifier, is_remix: '1' })
+
+      expect(response).to have_http_status(:not_found)
+    end
+
+    it 'responds 401 Unauthorized when the user cannot access the original project' do
+      inaccessible_project = create(:project, project_type: Project::Types::CODE_EDITOR_SCRATCH, locale: nil)
+      create(:scratch_component, project: inaccessible_project)
+
+      make_request(query: { original_id: inaccessible_project.identifier, is_remix: '1' })
+
+      expect(response).to have_http_status(:unauthorized)
+    end
+
+    it 'responds 400 Bad Request when no Scratch content is submitted' do
+      make_request(request_params: {})
+
+      expect(response).to have_http_status(:bad_request)
+    end
 
-    post '/api/scratch/projects', params: params, headers: cookie_headers
+    it 'creates a remix, associates it to the current user, and returns the new identifier' do
+      expect { make_request }.to change(Project, :count).by(1)
 
-    expect(response).to have_http_status(:ok)
+      expect(response).to have_http_status(:ok)
+      expect(response.parsed_body).to eq(
+        'status' => 'ok',
+        'content-name' => 'new-project-id'
+      )
 
-    data = JSON.parse(response.body, symbolize_names: true)
-    expect(data[:status]).to eq('ok')
-    expect(data[:'content-name']).to eq('new-project-id')
+      remixed_project = Project.find_by!(identifier: 'new-project-id')
+      expect(remixed_project.user_id).to eq(teacher.id)
+      expect(remixed_project.remixed_from_id).to eq(original_project.id)
+      expect(remixed_project.lesson_id).to be_nil
+      expect(remixed_project.scratch_component.content.to_h).to eq(scratch_project.deep_stringify_keys)
+    end
   end
 end