Step 1: Bake and cool cake. Place on foil-wrapped board, cut 1 in. larger than cake. Ice smooth with white buttercream, using a thick coat on sides. Comb sides with small-tooth edge of decorating comb.
Step 2: Attach White Sugar Sheets to left and right pages of book with piping gel. Trim bottom edges with scissors.
Step 3: Using Rotary Cutter, cut two rectangles, 9 3/4 long x 7 1/4 in. wide, from Light Pink Sugar Sheets Use border punch with Scallop Border Cutting Insert to cut scalloped edge on all sides. Attach to cake with piping gel, positioning 3/4 in. from side, 1 in. from top.
Step 4: Using Rotary Cutter, cut four strips, 5 long x 1/2 in. wide, from Light Pink and Bright Pink Sugar Sheets Attach to left page vertically with piping gel, alternating colors.
Step 5: Using Rotary Cutter, cut a rectangle, 5 long x 4 in. wide, from Light Pink Sugar Sheets Write message with black FoodWriter. Attach to center of right page with piping gel.
Step 6: Using cross cutter as a guide and black FoodWriter, trace shape on back side (shiny side) of White Sugar Sheets Cut cross out with scissors. Brush with piping gel and cover with white sparkling sugar. Attach to center of left page with piping gel.
Step 7: Using punch with Large Heart Cutting Insert, cut two hearts from Bright Pink Sugar Sheets Draw outline with black FoodWriter. Attach at corners of right page with piping gel.
Step 8: For bookmark, use Rotary Cutter to cut 10 1/2 long x 5/8 in. wide strip from Bright Pink Sugar Sheets Attach at center of cake with piping gel.
Step 9: Using tip 6 and buttercream, pipe bead bottom border. Draw details on scalloped edges with pink FoodWriter.