Preheat the oven to 350F / 175C. Grease a muffin tin.

In a bowl mix together sugar, vanilla, oil, and eggs. Add the cocoa, flour, baking powder, and salt. Stir well.

Fill each greased muffin tin ¾ full (I got 8). Bake for 25 minutes, or until the center is firm to the touch.

Cool in pan for 5 minutes and then make a dent in the middle of each brownie with the back of a spoon or the tip of a wooden spoon. Let it cool completely in the pan before removing it.

While the brownie cups are cooling, cut the chocolate into small chunks (or use chocolate chips).

Add milk chocolate and peanut butter to a small bowl and white chocolate and peanut butter into another small bowl. Melt each bowl of chocolate in the microwave for 1 and a half minutes, stopping every 30 seconds to stir. Mix well.

Divide the chocolate milk into the brownie cups (I left a teaspoon of this chocolate to decorate the cups at the end).

Let it stand for 5 minutes. Add the white chocolate over the milk chocolate. If desired, put the rest of the milk chocolate in a bag, cut the tip, and decorate the brownies.

Store in an airtight container for up to 3 days at room temperature. Enjoy with a glass of cold milk!