Preheat oven to 350°F. Spray 2 8-inch round cake pans with nonstick spray and set aside.
In a large bowl, combine the flour, cornstarch, cocoa powder, and baking soda. Stir together to combine, then set the bowl aside.
2¼ cups all-purpose flour, 2 tablespoons cornstarch, 2 tablespoons unsweetened cocoa powder, 1 teaspoon baking soda
In the bowl of a stand mixer fitted with the paddle attachment, beat the butter and sugar together until creamy. Add in the eggs, vanilla, and lemon juice, mixing to combine.
½ cup salted butter, 1½ cups granulated sugar, 2 large eggs, 1 teaspoon pure vanilla extract, 1 teaspoon lemon juice
Add in the flour mixture and milk, alternating, in two additions, to the butter mixture, mixing until well combined.
1 cup milk
Add in the food coloring, mixing on medium speed until the color is evenly distributed. You may add in an additional teaspoon of color, until it reaches your desired color.
2 tablespoons red food coloring
Evenly pour the batter into the prepared cake pans. Bake for 25-30 minutes, until an inserted toothpick comes out clean or the top of the cake springs back when touched.
Allow the cakes to cool before frosting. Cut any dome, or “tops”, of the cakes so they are both even and flat. Save the tops to crumble and coat/decorate the cake.