1. Prepare Your Oven and Pan: Preheat your oven to 350°F (175°C). Line an 8×8-inch square baking pan with parchment paper, leaving an overhang for easy removal. Grease the parchment lightly with butter or non-stick spray.

2. Mix Dry Ingredients: In a medium-sized bowl, whisk together the flour, cocoa powder, cornstarch, and salt. Set this aside for later.

3. Combine Wet Ingredients: In a large mixing bowl, whisk the melted butter and granulated sugar until smooth and creamy. Add the eggs, vanilla extract, and red food coloring, and whisk until fully combined and vibrant. Stir in the white vinegar for that signature tanginess.

4. Mix the Batter: Gradually fold the dry ingredients into the wet mixture using a spatula. Avoid overmixing to ensure the brownies stay tender. If using, gently fold in the white chocolate chips for an extra layer of sweetness.

5. Bake the Brownies: Pour the batter into the prepared pan and spread it evenly with a spatula. Bake for 28–32 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs. Allow the brownies to cool completely in the pan.

6. Make the Cream Cheese Frosting: In a mixing bowl, beat the softened butter and cream cheese together until smooth. Gradually add the powdered sugar, mixing on low speed to prevent a sugar cloud. Add the vanilla extract and salt, and beat until fully incorporated. If the frosting is too thick, add 1 tablespoon of whipping cream to reach your desired consistency.

7. Frost the Brownies: Once the brownies are completely cool, spread the cream cheese frosting evenly over the top. Cut into squares and serve.