Beat first 4 ingredients in a large bowl at medium speed with an electric mixer until blended. Stir in oranges. Pour batter into 3 greased and floured 8-inch round cakepans. (Layers will be thin.)
Bake at 350° for 25 to 30 minutes or until a wooden pick inserted in center comes out clean. Cool layers in pans on wire racks 10 minutes; remove layers from pans, and let cool completely on wire racks.
Stir together crushed pineapple and next 3 ingredients. Spread pineapple mixture evenly between layers and on top of cake. Chill cake 3 to 4 hours. Garnish, if desired. Store cake in refrigerator.