Preheat oven to 350F.

Spray an 8x8 pan with baking spray and line with parchment, then set aside.

In a large bowl, combine the melted butter and granulated sugar. Whisk vigorously until completely blended, then vigrously whisk in the eggs, one at a time. Mixture should be thick and bright yellow.

Add 1 1/2 tsp vanilla extract, distilled white vinegar, and red food coloring, and whisk vigorously until ingredients are completely combined and mixture is bright red. Set aside.

In a medium bowl, whisk together the flour, cocoa powder, baking powder, and salt.

Sift dry ingredients into the wet ingredients in small amounts, gently stiring with a wooden spoon or spatula between additions until all ingredients are completely combined.

Pour red velvet brownie batter into prepared baking pan. Bake at 350F for 30-45 minutes, or until a toothpick inserted in the center of the brownies comes out clean.

Remove brownie pan to wire rack. Let brownies cool completely before cutting and/or frosting. Serve with Cream Cheese Frosting (see below) if desired.

In a large bowl, beat together the 4 tbsp softened butter and softened cream cheese using a hand-mixer or stand-mixer until completely combined.

Beat the confectioner's sugar into the mixture, bit by bit, until frosting is thick but spreadable.

Beat in the 1/4 tsp vanilla extract until combined.

Spread or pipe Cream Cheese Frosting onto cooled Red Velvet Brownies. Store frosted brownies and leftover frosting in the refrigerator.