Combine the flour, salt and cocoa powder in a bowl. Set aside.

In a separate bowl, beat the sugar and oil with an electric mixer. Add the eggs, food coloring and vanilla extract and mix well. Add the flour mixture in 2 additions, alternating with the buttermilk.

In a small bowl, combine the baking soda and vinegar. Add this to the batter and mix to combine.

Grease and flour the cake pans and divide the batter between the pans. Bake at 350F for 40-50 minutes. Cool in the pan for 5 minutes, then turn out onto a wire rack and cool completely.

To make the frosting, beat the cream cheese and butter with an electric mixer until smooth. Add the vanilla extract and powdered sugar one cup at a time, beating with each addition.

Spread the cream cheese frosting into the heart portions of the cakes, then stack them together as shown in the video. Transfer the cake to a cake stand and coat the entire surface in a thin layer of frosting. Chill in the fridge for 20 minutes.

Coat the entire cake in a generous layer of frosting. Press the sprinkles halfway up the sides of the cake. Slice to reveal the heart inside and enjoy!