1Heat oven to 350°F (325°F for dark or nonstick pan). Generously spray bottom and side of 8- or 9-inch round cake pan with baking spray with flour.
2In large bowl, beat cake mix, water, oil and egg whites with electric mixer on low speed until moistened, then on medium speed 2 minutes, scraping bowl occasionally. Pour into pan.
3Bake as directed on box for 8- or 9-inch round. Cool 10 minutes. Remove cake from pan to cooling rack. Cool completely, about 1 hour.
4Spread lemon curd on top of cake to within 1 1/2 inches of edge. In decorating bag with star tip, place about 1/2 cup frosting; set aside. Spread remaining frosting on side and up to edge of lemon curd on top of cake. Place raspberries in circle on top of cake where frosting and lemon curd meet. Pipe reserved frosting along lower edge of cake. Store loosely covered in refrigerator.