Step 1: Preheat the Oven and Prepare the Baking Pan

Preheat your oven to 350°F (175°C). Line an 8×8-inch baking pan with parchment paper. This will prevent the brownies from sticking and make cleanup easier. Ensure that the parchment paper extends slightly over the edges so that the brownies can be lifted out easily once baked.

Step 2: Melt the Butter and Chocolate

In a large microwave-safe mixing bowl, melt the butter and chopped semi-sweet chocolate in the microwave in 30-second increments, stirring after each interval. Continue until the mixture is fully melted and smooth. Allow it to cool slightly before proceeding to the next step.

Step 3: Add Sugar, Eggs, and Flavorings

Whisk the granulated sugar into the melted chocolate and butter mixture until fully combined. Then, add the eggs one at a time, beating well after each addition. This helps incorporate air into the batter, which contributes to a smooth texture. Stir in the vanilla extract, white vinegar, and red food coloring, mixing until the color is evenly distributed.

Step 4: Mix the Dry Ingredients

In a separate bowl, sift together the cocoa powder, all-purpose flour, and salt. Sifting prevents lumps and ensures that all dry ingredients are evenly combined.

Step 5: Combine Wet and Dry Ingredients

Gradually add the dry ingredients to the wet mixture, stirring gently until just combined. Be careful not to overmix, as this can result in dense or tough brownies. If using white chocolate chips, fold them in at this stage.

Step 6: Bake the Brownies

Pour the brownie batter into the prepared 8×8-inch pan, spreading it evenly. Bake in the preheated oven for approximately 30-35 minutes. The brownies are done when a toothpick inserted in the center comes out with a few moist crumbs but no wet batter.

Step 7: Cool and Serve

Allow the brownies to cool completely in the pan before slicing them into squares. If desired, drizzle melted white chocolate on top before serving.