Preheat the oven to 350°F (177°C) and grease or line a 12 cup muffin pan.

In a medium bowl whisk together the melted butter and 200g granulated sugar until thick and glossy.

Add the eggs one at a time, whisking well after each addition, then mix in the vanilla extract and red food coloring until evenly distributed.

Stir in the buttermilk and distilled vinegar until smooth and well combined.

In a separate bowl whisk together the flour, cocoa powder, baking powder, baking soda, and salt to remove lumps.

Gently fold the dry ingredients into the wet ingredients until no dry streaks remain, being careful not to overmix.

In another bowl, beat the softened cream cheese with 50g granulated sugar until smooth and creamy.

Add the egg yolk and vanilla extract to the cream cheese mixture and beat until silky and thick but spoonable.

Spoon about 15ml of red velvet batter into each muffin cup, filling them halfway.

Add a rounded teaspoon of cream cheese filling to the center of each cup on top of the red velvet batter.

Cover the cream cheese filling with another spoonful of red velvet batter, filling the cups about 3/4 full.

Use a toothpick or skewer to gently swirl the cream cheese through the red batter in each cup, creating a marbled pattern.

Bake the brownie bites for 18 to 22 minutes, or until the edges are set and a toothpick comes out with a few moist crumbs.

Remove the pan from the oven and let the brownie bites cool in the pan for 10 minutes.

Carefully transfer the brownie bites to a wire rack and let them cool completely.

For a decorative finish, crumble one cooled brownie bite into fine crumbs and sprinkle over the remaining bites before serving.