1. Preheat your oven to 350°F. Line a 9×13-inch baking pan with parchment paper and grease lightly.

2. In a large bowl, whisk together melted butter, granulated sugar, and brown sugar until smooth.

3. Add in the egg, vanilla extract, vinegar, and red food coloring. Stir until fully combined.

4. Fold in flour, cocoa powder, baking soda, and salt. Mix just until the dough comes together.

5. Spread dough evenly into the prepared baking pan.

6. Bake for 18–22 minutes, or until edges are set and center is slightly soft. Let cool completely.

7. While cooling, beat cream cheese and softened butter until creamy. Gradually add powdered sugar and beat until fluffy.

8. Spread frosting over cooled bars.

9. Slice into squares and decorate with sprinkles if desired.

10. Store bars in the fridge for up to 5 days, or freeze for later enjoyment.