Prepare 1 box of cake mix according to package directions for two 9-inch cakes. Prepare the other cake mix for regular and mini cupcakes; bake in white cupcake liners. Let cakes cool completely.
Place one 9-inch cake on serving platter. Frost top with vanilla frosting. Place other layer on top, and frost entire cake. (This should take about 1-1/4 cans of frosting).
Place 1/3 cup of remaining frosting in a small bowl. Tint yellow, transfer to a resealable plastic bag, and snip off a corner. Divide remaining frosting between 2 bowls. Tint one bowl blue and the other pink. Frost regular cupcakes blue and mini cupcakes pink. Place remaining pink frosting in a bag with a ribbon tip attached. Transfer remaining blue frosting to a bag with a #3 tip. Pipe vertical pink ribbon lines around side of cake, leaving space between lines. Pipe blue lines next to pink lines. Pipe rows of yellow dots next to blue lines. Stack mini cupcakes, with candles inserted (see directions below), on top of bigger cupcakes, and place on top of cake.
Line a baking sheet with wax paper. In microwave, heat white-chocolate chips on medium power, stirring every 20 seconds, until melted. Spoon into a resealable bag, and snip off a corner. Pipe 30 lines about 1/4-inch wide onto the sheet of wax paper. Place the yellow, orange, and red melting wafers into separate resealable plastic bags. Microwave bags, 20 seconds at a time, on medium power until wafers are melted. Pipe yellow flames on top of lines. Pipe a small dot of red or orange in the center of yellow. Transfer the baking sheet to the refrigerator until candles are set, about 5 minutes. Carefully insert candles into tops of mini cupcakes before stacking.