Preheat oven to 400º. Grease or line 9 cavities of a cupcake pan. Grease a square 8x8 pan. Set aside.

Add all cake ingredients to a mixing bowl and beat for 2 minutes.

Fill NINE greased or lined cupcake cavities 3/4 full. Place in oven for 12-14 minutes, or until a toothpick inserted in the center of the cupcakes comes out clean.

As the cupcakes bake, pour the remaining batter into greased 8x8 square pan. Once the cupcakes are removed from the oven, reduce heat to 350º and bake the cake for 30-35 minutes, or until a toothpick inserted in the center comes out clean.

Cool cake and cupcakes completely.

Once cool, cut each cupcake in half, and cut the square cake into nine equal pieces (cut it into thirds horizontally and vertically).

Using store-bought frosting or Simple Buttercream Frosting, "glue" 2 cupcake halves next to each other on one cut square (using adjacent sides). If your cupcakes don't match up evenly with the lines of the square cakes, use a sharp knife to carve as necessary to achieve desired heart shape.

Repeat with all cupcakes and cake squares. If the cake is very soft, cover and freeze to make frosting it easier. Otherwise, you will be dealing with a lot of crumbs when you spread your frosting.

Place Mini Heart Cake on a sheet of parchment to make transferring and cleanup easier. Spread a thin layer of frosting over the entire cake (a crumb coat). Refrigerate until the crumb coat is set. (If your cake didn't produce crumbs while frosting, feel free to omit the crumb coat and start decorating!)

Frost and decorate as desired.