Melt your chocolate according to the instructions on the package.
You can also melt the chocolate in a heat proof bowl in the oven on the lowest setting. It takes about 20-30 minutes to melt 12 oz of chocolate.
Once the chocolate is melted, add 1-2 tsp of melted chocolate to each heart and spread around using a paint brush, spoon, or other utensil. After you’ve spread the frosting along the sides of the mold, you can shake the mold to get it even.
The amount of chocolate you will need per heart needed will vary depending on the size of your silicone molds.
If necessary, add more chocolate to the edges of the heart molds as those are common areas that can break when removing the hearts.
Be sure to view the heart molds from all different sides and angles. Its easy to miss spots and then the hearts break when removed.
Let chill in fridge 5-10 minutes until hard.
While the chocolate hardens, make the cake mix by adding the frosting to the cake and mix using a spatula or your hands. It should come together when you press it but not be too wet with frosting. Remember you need way less frosting than you think. If it's dry add a bit more frosting, 1 tsp at a time.
Remove from the mold from the fridge and add 1-2 tsp of cake mix to each heart leaving room from at the top for more chocolate. Again the exact amount of cake mix can vary depending on the mold.
Spoon another teaspoon of chocolate on the cake mix in the molds and using a bench scraper or knife scrape the chocolate chocolate off the top of the mold.
Let harden. Once the chocolate has completely hardened, gently remove the hearts from the silicone mold.