1. Preheat oven to 325 degrees F. In a medium bowl combine graham cracker crumbs, butter, and brown sugar with a fork until it is a course crumble. Dump the mixture into a 8x8 baking dish (a 11x7 would also work but have a thinner crust), and press the mixture down into the dish until it's even and pressed together. Bake for 10 minutes, remove and cool (leaving in baking dish) for at least 30 minutes.

2. Increase oven temperature to 350 degrees F. Beat cream cheese, egg, sugar, and vanilla extract together with a hand or stand mixer until smooth and creamy, about 3 full minutes. Make sure there are no clumps.

3. Spread the Peanut Butter M&Ms in a layer over the crust. Pour the cream cheese filling over this layer and use a spatula to spread evenly. Bake for 30 minutes. Remove from oven and top with mini M&M's, then place back in the oven and cook for an additional 20-25 minutes or until set. Cool completely (at least 1 hour), and then refrigerate for at least 3 hours prior to serving.

4. Cut into bars and serve.