Preheat oven to 375° F.
Combine flour, baking soda and salt in small bowl. Beat butter, granulated sugar, brown sugar and vanilla extract in large mixer bowl until creamy. Add eggs, one at a time, beating well after each addition. Gradually beat in flour mixture. Stir in chocolate chips.
Grease or use a coated 15 x 10-inch jelly-roll pan. Spread cookie dough into prepared pan. Bake for 10-15 minutes or until golden brown. Cool in pan on wire rack.
After cookie has cooled for about 5 minutes, add peanut butter in dollops all over the cookie. Allow to melt and spread almost to the edge of the pan.
Next, roughly crush Plain and Peanut Harvest M&M’s in a ziploc bag and sprinkle over smoothed peanut butter.
Break up Reese’s Cups and Snickers bar and crumble over cookie.
Allow to cool and harden a little before serving.