Step 1

Line an 8x8 baking dish with tin foil or parchment paper. Doing this will make the bars easier to lift out and cut into squares.

Step 2

In a mixing bowl, combine butter, brown sugar, and sugar. Beat together with a hand mixer until combined and creamy.

Step 3

Add the peanut butter and vanilla extract. Beat together until combined.

Step 4

Add flour, oats, and m&m's and beat on low speed until combined.

Step 5

Press into prepared pan.

Step 6

To make the topping: In a microwave safe bowl melt the chocolate and heavy cream for 2 minutes, stirring every 30 seconds. *It may not take the entire 2 minutes until it's melted. That's ok.

Step 7

Pour the milk chocolate over the cookie dough bars and spread out evenly. Immediately sprinkle with remaining M&M's.

Step 8

Cover the pan with tin foil and refrigerate for 2 hours. Lift the bars out by the overhang of the foil or parchment paper and cut into squares. Store the bars in the fridge.