Step 1

Preheat the oven to 350 degrees F.

Step 2

Line an 8×8-inch or 9×9-inch pan with parchment paper, crossing two sheets on the bottom of the pan so that the parchment overhangs each side of the pan for easy removal.

Step 3

In a large microwave-safe bowl, add the butter and the chocolate chips and microwave in 15-second intervals, stirring after each interval, until it is melted and smooth.

Step 4

Add the brown sugar and the sugar to the melted chocolate mixture and whisk until incorporated.

Step 5

Add the eggs, 1 at a time, to the melted chocolate mixture and thoroughly combine after each addition.

Step 6

Add the vanilla to the chocolate mixture and mix to combine.

Step 7

Add the flour, the cocoa powder, and the salt to the chocolate mixture and whisk until the batter is smooth.

Step 8

Pour 1/2 of the brownie batter into the prepared pan and use a spatula to spread it all the way to the corners and sides of the pan.

Step 9

In a microwave-safe bowl, add the white chocolate, the peanut butter, and the sweetened condensed milk and microwave in 15-second intervals, stirring after each interval, until it is completely melted together and thick.

Step 10

Pour the peanut butter fudge on top of the brownie batter in the baking pan and use a spatula to evenly spread it out.

Step 11

Pour the remaining brownie batter on top of the peanut butter fudge and use a spatula to evenly smooth it out.

Step 12

Bake the brownies until a toothpick inserted into the center comes out clean, about 40 minutes.

Step 13

Let the brownies cool completely.

Step 14

Cut and serve.