• Preheat oven to 350°F. Line a 9x13-inch baking pan with aluminum foil and spray it with nonstick baking spray.

For the Cookie Crust:

• Beat the butter and sugars until light and fluffy.
• Add the peanut butter and beat until creamy.
• Add the eggs and vanilla and beat again.
• Stir together the salt, baking soda, flour, and oats in a bowl. Slowly add the dry ingredients to the butter mixture and beat until incorporated.
• Add the milk and beat again.
• Stir in the chocolate chips and 3/4 c. M&M's candies by hand.
• Press half the cookie dough into the bottom of the prepared pan. Set aside; reserve remaining dough.

For the Cheesecake:

• Beat the cream cheese until creamy.
• Add the granulated sugar and beat until smooth.
• Add the melted chocolate and beat until creamy.
• Add the eggs one at a time, beating well after each addition. Make sure the eggs are fully incorporated, but do not overbeat the batter.
• Spread the cheesecake batter over the cookie dough in the pan. Crumble the remaining cookie dough over the cheesecake batter.
• Sprinkle the remaining M&M's on top.
• Bake for 35-40 minutes.
• Remove the pan from the oven and place it on a wire rack for 1 hour, then refrigerate for 4 hours or until completely chilled.
• Cut it into 24 bars before serving.