Bake your favorite 2-layer cake recipe or mix in 8 in. heart pan following recipe instructions. Cool in pan on cooling grid 15 minutes; remove from pan and cool completely. Stack layers on foil-wrapped cake board cut to size.
Tint buttercream icing light rose; spatula ice cake. Using 2nd largest heart cutter, imprint heart in icing on top of cake. With toothpick, mark garlands 1-1/2 in. deep x 2-1/2 in. wide on side of cake. Thin a portion of white buttercream with corn syrup; pipe tip 2 sotas between markings on top and sides of cake. Outline heart and garland with tip 16.
Add tip 21 white rosette bottom border; attach jumbo heart sprinkles. Add icing decorations at garland points and in center of heart with dots of icing.