This is the info that came in the box with my heart-shaped cake/brownie tins:
Use 1 two-layer cake mix to make 24 cupcakes. Also use brownie or muffin mix.
Preheat oven to 350.
Grease and flour the pans.
Pour ¼ c batter into each mold
Bake on middle rack for 15-20 min.
Cool 5 min and trim so cakes sit level. Unmold and cool ½ hour before decorating.
Buttercream icing:
½ c butter
½ c shortening
1 t vanilla
4 c sifted powdered sugar
2 T milk
Cream butter and shortening with electric mixer, add vanilla. Add sugar gradually, one cup at a time, beating well on medium speed. Scrape sides and bottom of bowl often. Icing will appear dry when all sugar is added. Add milk and beat at high speed until light and fluffy. Keep icing covered with a damp cloth until ready to decorate. Refrigerate unused portion. Keep for up to 2 weeks in airtight container. Makes 3 cups.
To ice smooth: Place icing on cake with spatula, then spread lightly with spatula in one direction over area.
To outline, use Tip #3 and constant pressure.
To pipe stars, use Tip #16, squeeze and pull away.
To pipe dots, use Tip #3, squeeze and keep point in there until dot is size you want.
To pipe heart, use Tip #3, pipe a large shell with decreasing pressure to form a point. Then pipe a second shell that hooks up with first to form a heart.