01 -
Preheat the oven to 350°F (177°C). Grease or line an 8×8 inch baking pan with parchment paper.
02 -
In a microwave-safe bowl, melt butter and chopped chocolate in 30-second intervals, stirring after each until smooth.
03 -
Add granulated sugar to the melted butter and chocolate mixture. Mix using an electric mixer on medium speed until fully combined.
04 -
Add eggs one at a time, beating well after each addition. Stir in vanilla extract, white vinegar, and red gel food coloring until homogenous.
05 -
In a separate bowl, sift together cocoa powder, all-purpose flour, and salt.
06 -
Gradually add the dry ingredients to the wet ingredients, mixing gently until just combined without overmixing.
07 -
Fold in desired mix-ins such as white chocolate chips or chopped nuts if preferred.
08 -
Pour batter into the prepared pan and spread evenly. Bake for 25-30 minutes or until a toothpick inserted near the center comes out with moist crumbs.
09 -
Allow to cool completely in the pan at room temperature before slicing into 16 squares.