Cookies: Preheat oven to 350°F. Whisk together flour, baking powder, baking soda and salt.
Using electric mixer, beat together butter, granulated sugar and brown sugar until light and fluffy; beat in egg and vanilla. Stir in flour mixture until combined. Fold in chopped M&M’s® Milk Chocolate.
Divide cookie dough into 36 portions. Roll into balls and place on parchment paper-lined tray; flatten slightly. Freeze for 10 minutes.
Transfer cookies from cold tray to 2 room temperature parchment paper-lined baking sheets, about 2 inches apart. Bake one sheet at a time in centre of oven for 9 to 12 minutes or until lightly golden on the bottom and tops are set. Let cool completely.
Dip: Beat together butter, icing sugar, milk and vanilla until smooth. Beat in whipped topping until smooth. Fold in chopped M&M’s® Milk Chocolate. Serve with cookies for dipping. Tip: Serve each portion as individual snack packs for gatherings.