Step 1: Preheat your oven and prepare an 8x8 or 9x13 inch baking pan according to the brownie mix instructions.
Step 2: Prepare the brownie mix according to package directions. Pour the batter into the prepared baking pan and bake as directed.
Step 3: Once the brownies are baked, remove them from the oven and immediately spread the 7 ounces of marshmallow creme evenly over the hot brownies. This will help it melt and spread easily.
Step 4: In a large microwave-safe bowl, combine the semi-sweet chocolate chips and creamy peanut butter. Microwave in 30-second intervals, stirring after each, until smooth and fully melted.
Step 5: Add the crispy rice cereal to the melted chocolate-peanut butter mixture. Stir until the cereal is completely coated.
Step 6: Spread the crispy peanut butter mixture evenly over the marshmallow layer. Gently press it down to ensure it adheres.
Step 7: Sprinkle the halved Reese's miniatures over the top of the crunch layer, pressing them lightly so they stick.
Step 8: Allow the brownies to cool completely at room temperature, or chill in the refrigerator for about 30 minutes, before cutting into squares and serving.