Cake serves 12.
Bake your favorite 1-layer cake recipe or mix in round pan. Cool cake in pan on wire rack 10 minutes. Remove from pan and cool completely. Place on foil-wrapped cake circle.
Using spatula, ice cake smooth in buttercream.
Position "Happy Birthday" stencil. Sprinkle different colored sugars over stencil openings. Carefully remove stencil. Decorate bottom border with tip 18 zigzag garland. Sprinkle border with assorted colored sugars. Decorate cake sides with tip 16 stars. Edge cake top with tip 18 rosettes; insert candles in rosettes.