Prep. Preheat the oven to 375°F. Line two baking sheets with silicone baking mats or parchment paper.
Cream butter and sugar. In a large bowl, using a mixer, cream 1 cup softened butter, 1 cup brown sugar and 3/4 cup granulated sugar for 1 minute. Add 2 eggs and 2 teaspoons vanilla and mix until combined.
Add dry ingredients then chill dough. Add 3 cups flour, 1 teaspoon baking soda and 1/2 teaspoon salt and stir mix just until combined. Fold in 1 cup chopped candy bars and 1 cup M&M’s.
Scoop dough. Using a large cookie scoop (about 3 Tablespoons), scoop the cookie dough onto the baking sheet about 2 inches apart. Place extra M&M’s and candy bar pieces on the top of the cookies if desired. Refrigerate dough balls on pan for 30 to 60 minutes.
Bake. Bake for 7-10 minutes, or until the edges are barely golden brown. Allow cookies to set on pan for 2-3 minutes, and then remove to a cooling rack. Store in an airtight container for up to 3 days.
Notes
Candy: I love to use mini Milky way, Snickers, Reese's, Hershey's or Rolos.Thicker cookies: If you'd like a thicker cookie, add in 1 Tablespoon of cornstarch and refrigerate the dough balls the full 60 minutes.Storage: Store in a covered container up to 3 days. Freeze in a covered container up to 3 months.