Preheat oven at 350ºF/180ºC. Line one round baking pan and one square baking pan with parchment paper.
Start by adding the wet ingredients. Beat the eggs, sour cream, melted butter, and vanilla extract. Combine well.
In a separate bowl, combine dry ingredients (almond flour, coconut flour, cocoa powder, erythritol and baking powder).
Add the dry ingredients into the wet mixture, and finally add the red food coloring. Combine well.
Divide the batter into the pans and bake in the oven for about 30 minutes. or until a toothpick inserted into the center of the cake comes out clean. Let it cool completely on a wire rack.
Cut the circle cake in half evenly.
Position the square cake so it looks like a diamond, then place each half of the circle cake on the two sides of the square cake.
Place the mascarpone in the bowl of a stand mixer with the whisk attachment and start beating on medium speed. While beating, add the vanilla extract and the low carb powdered sugar. Scrape sides and continue beating until light and fluffy.
With the mixer running on high speed, slowly add the heavy cream until the frosting becomes light and fluffy, about 1-3 minutes. DO NOT OVERMIX.
Spread onto the Heart-Shaped Cake. Add sprinkles or whatever you want.
If you don’t have one, use wax paper or parchment paper and place the cake where you plan to serve it.
The frosting will fill in the imperfections and it will connect the 3 pieces like magic!