How to Make It
Whisk together first 2 ingredients. Line bottom and sides of a 6-qt. slow cooker with aluminum foil, allowing 2 to 3 inches to extend over sides. Lightly grease foil with cooking spray.
Combine flour and next 5 ingredients, and whisk until smooth. Pour flour mixture into slow cooker. Pour lemon curd mixture on top. Cover and cook on High for 2 hours. (Center will be soft.) Remove lid, and cool completely. Lift cake from slow cooker, using foil sides as handles. Dust cake with powdered sugar.