In an extra large mixing bowl, add eggs 3) and both sugars (1 1/2 cups brown + 1 cup sugar) and combine well. Mix in vanilla (1 tablespoon), corn syrup (1 teaspoon), salt (1/2 teaspoon), baking soda (2 teaspoons), butter (1/2 cup), and peanut butter (1 1/2 cups), and combine well. Mix in oats (4 1/2 cups). Add chocolate chips (1 cup), butterscotch chips (1 cup), and M&M's (1 cup). Mix until evenly distributed.
Using a large cookie scoop, put on an ungreased cookie sheet. Bake in preheated oven for 12-15 minutes
Notes
Don’t Overbake. Pull them when the centers look just slightly underdone. They’ll firm up as they cool, and that’s how you keep them soft.
Want Thicker Cookies? Refrigerate the dough for 30 minutes before baking. Chilling reduces spread and creates even puffier cookies.
Use Light-Colored Baking Sheets. Dark pans can cause over-browning on the bottoms before the centers finish baking.
Customize the “Monster”. Add chopped peanuts for crunch, white chocolate chips for sweetness, or swap butterscotch for extra chocolate.