If you don't want to make the mini cupcakes, you can purchase a box of chocolates to add to the top of your cake.
Bake the cake and the mini muffins according to package directions. If you use an 8-inch round pan, 1 box of cake mix should be enough to make the cake and at least 12 mini cupcakes. If you use a larger heart pan you may need 1 1/2 boxes of cake mix. If your mix doesn't have directions for the mini muffins, bake them for about 12 to 15 minutes, and check for doneness.
Set the cake and the mini cupcakes aside to cool.
Melt the chocolate according to the package directions.
Let your kids help dip the tops of the mini cupcakes into the chocolate, and set them aside to cool and harden. If you're adding nuts to the tops of some of the cupcake "chocolates," add them while the chocolate is still melted.
If you want, you can drizzle the top of a couple of the "chocolates" with white or dark chocolate. Using a spoon or pastry bag and some white chocolate melted according to the package directions.
Cover your cake board with aluminum or decorative foil.
When the cake is cool, level it cake with a serrated knife and place it on the cake board covered with decorative foil.
Ice the cake with chocolate icing.
Set the cake aside to let the icing dry for about 15 minutes.
When the icing is dry, you're ready to make the basket weave. Fill a pastry bag with chocolate icing and use a basket weave decorator tip (like Wilton #47 tip). Start decorating by putting squeezing one strip of icing down the side of the cake.
NOTE: You can also use a star tip or a flat sided tip for your weave. Different tips will give your weave a different look, but many will work.
Once you have one vertical stripe down the side, pipe several short horizontal lines going across the vertical stripe and continuing on for about an inch on the other side. Leave room between each horizontal stripe about the width of the decorator tip so you can insert a row between later.
Make another vertical stripe down the cake going just over the ends of the horizontal stripes you just made. Repeat the horizontal stripes, but bury the beginning of the next set of horizontal lines under the first vertical line, in the spaces you left between your first set of horizontal lines, so it looks like the weave is coming out from underneath.
Repeat the process all the way around the side of the cake.
You can finish the cake off with a border around the top and/or bottom of the cake. To make the shell border pictured here, use a star decorating tip (like Wilton # 32) and pastry bag. Place the tip just above the cake where you want to make your first shell. Squeeze your hand to apply pressure and squeeze out some of the icing while you lift slowly and pull slightly forward; release the pressure and lift up. Put the tip right above the end of the first shell and repeat the process. Repeat this motion all the way around the cake to make a shell border.
Place your mini cupcake "chocolates" on top of the cake.