Once your sheet cakes have chilled completely use your desired cutter (I used a 3” heart cutter) to cut out as many cakes as possible, about 16. Cold cakes are easier to cut, and handle and are less crumbly.
Set the cake on a small cake board so you can easily move it.
Torte the little cake in half moving slowly with a serrated knife and turning the cake as you cut. You will have a thin cake layer, so handle it gently. (Optional)
Pipe a dam of buttercream around the edge of the cake.
Fill the center of the dam with a few Tablespoons of filling.
Place the next layer of cake on top. If your cakes are very soft and sliding, let them rest in the freezer for 15-30 minutes to firm up.
With a small offset spatula, coat the exterior of the cake with your desired base color, then do a second layer of buttercream. Complete all of the buttercream coats before moving on to piping the edges and decor.
Practice your piping design briefly on a piece of parchment so you know you like it. It will be easier to scrape off the parchment than the cake!
Now you can get creative and make these cakes as ornate or as simple as you like.
Finish your design with cute messages on top.
Once you are finished decorating all of your mini cakes, place them in the freezer to set. It will be much easier to move them without messing up the design if the buttercream is frozen.
Remove the cake from the cake board with an offset spatula or knife.
Place a sheet of parchment paper in a little to-go container, add the cake inside, and add a fork on top.
If you are not serving these right away, wrap them in plastic wrap and keep them in the freezer until you are ready to package. Also, you could package them, wrap the box in plastic wrap and keep them in the freezer. They will keep up to 2 months in the freezer.