Let’s break down the process of making these Mint Oreo™ M&M’s™ Brookies into easy-to-follow steps. I’ll walk you through each stage, making sure it’s clear and straightforward.

Step 1: Prepare the Pan. Heat your oven to 350°F (175°C). Line a 9-inch square pan with foil, allowing the foil to hang over the sides of the pan. This will make it easy to lift the brookies out later. Grease the foil with cooking spray.

Step 2: Make the Brownie Batter. Prepare the brownie batter according to the directions on the box, using the specified amounts of water, oil, and eggs. Whisk until just combined – don’t overmix.

Step 3: Bake the Brownie Layer. Spread the brownie batter evenly in the prepared pan. Bake for 32 to 35 minutes, or until a toothpick inserted into the center comes out with moist crumbs (not wet batter). The edges should be set.

Step 4: Cool Slightly. Remove the brownies from the oven and let them cool in the pan for 10 minutes. This is important, as it allows the brownie layer to set up slightly before adding the cookie dough.

Step 5: Make the Cookie Dough. While the brownies are cooling, prepare the cookie dough according to the directions on the pouch for drop cookies. This usually involves mixing the cookie mix with softened butter and an egg.

Step 6: Add the M&M’s®. Stir 1 cup of the green M&M’s® into the cookie dough.

Step 7: Layer the Cookie Dough and Oreos™. Drop half of the cookie dough mixture in chunks on top of the baked brownie layer. Add half of the chopped Oreo Thins™ pieces. Repeat with the remaining cookie dough and Oreo™ pieces.

Step 8: Spread and Top. Use the back of a spoon or an offset metal spatula to gently press the cookie dough together, forming an even layer over the brownies. Top with the remaining 1/4 cup of M&M’s®, pressing them gently into the cookie dough.

Step 9: Bake Again. Bake for 23 to 28 minutes, or until the cookie layer is set. If the top starts to brown too quickly, cover it loosely with foil for the last 10 minutes of baking.

Step 10: Cool Completely. Let the brookies cool completely in the pan for at least 2 1/2 hours. This is crucial for allowing them to set up properly and making them easier to cut. Once cool, lift them out of the pan using the foil overhang and cut into squares.