Combine brownies, condensed milk and peanuts for a quick, easy, and delicious dessert. Make the recipe ahead and freeze.
Preheat oven to 350 degrees F. Lightly grease a 13x9x2-inch baking pan; set aside. In a large bowl, combine brownie mix, eggs, and oil. Beat with an electric mixer on medium speed until combined. Stir in peanuts. Remove half of the brownie mixture and set aside. Spread the remaining brownie mixture evenly into prepared pan.
In a medium bowl, whisk together sweetened condensed milk and peanut butter until smooth. Spread evenly over brownie mixture in pan. Separate the remaining brownie mixture into pieces, flatten them with your fingers, and place them on top of the brownie mixture in pan.
Bake in the preheated oven for 25 to 30 minutes or until top is set and edges are lightly browned. Cool completely in pan on a wire rack. Cut into bars. Makes 32 bars.
Layer cookies between waxed paper in an airtight container; cover. Store at room temperature for up to 3 days or freeze for up to 3 months.