Step 2: Line an 8×8 inch baking pan with parchment paper.
Step 3: In a medium bowl, whisk together the flour, cocoa powder, and salt.
Step 4: In a large mixing bowl, combine the melted butter, granulated sugar, and brown sugar. Mix well, then add the eggs one at a time, mixing well after each addition. Stir in the melted chocolate, vanilla extract, and vinegar. Add red food coloring as desired.
Step 5: Fold the dry ingredients into the wet mixture until just combined.
Step 6: Pour the batter into the prepared pan and bake for 20-25 minutes.
Step 7: While cooling, beat together cream cheese and butter until smooth. Gradually add powdered sugar, then vanilla and salt.
Step 8: Once brownies are cool, frost with cream cheese frosting.
Step 9: Cut into squares and serve.
Notes
Store leftovers in an airtight container at room temperature for up to 3 days or in the fridge for up to a week.