These Brownie Peanut Butter Cups nestle a creamy peanut butter filling inside a chewy brownie shell, with chocolate and peanut butter chips sprinkled over the top for good measure. Talk about a crowd-pleasing dessert!
Combine the sugar, butter, and water in a microwave-safe bowl and heat on high for about 1 minute, or until the butter melts. Stir in 3/4 cup semisweet chocolate chips, and once they melt, stir in the egg and vanilla extract.
Add the flour and baking soda to the wet ingredients and stir to combine. Let the mixture come to room temperature, then fold in 1/2 cup of peanut butter chips and 1/2 cup of semisweet chocolate chips.
Divide the batter evenly into the prepared muffin cups, then bake for 13 to 15 minutes, or until the tops are set and a toothpick inserted into the center comes out slightly wet.
Set the pan on a wire rack and let the brownies cool until the centers fall; if they don’t fall, you can use a teaspoon to gently push on the centers to create an indentation. Don’t let the brownies cool completely!