Heat oven to 350°F.
Combine flour, baking powder, baking soda and salt in bowl. Set aside.
Combine sugar and butter in bowl. Beat at medium speed, scraping bowl often, until creamy. Add 1 egg at a time, beating well after each addition. Add sweet potatoes and orange zest. Beat at low speed, gradually adding flour mixture alternately with milk, until well mixed.
Spoon batter into 2 greased (9-inch) round cake pans. Bake 25-35 minutes or until toothpick inserted in center comes out clean. Cool 10 minutes; remove from pan. Spread 1/4 cup marmalade over top of each warm cake.
Cut into wedges; dollop with whipped cream, if desired.
Cake can be baked in greased and floured 10-inch angel food (tube) cake pan or 12-cup Bundt® pan. Bake 50-55 minutes. Cool in pan 15 minutes.