Source: https://mygluten-freekitchen.com/monster-cookies-gluten-free/
Ingredients
Preheat oven to 350°. Line cookie sheets with parchment paper.
In the bowl of your electric mixer, cream together butter, sugars, peanut butter and eggs until light.
Add baking soda, vanilla extract, and gluten-free oats and mix on low speed until well mixed.
Stir in chocolate chips and plain M&M's.
Use a large cookie scoop to scoop rounded balls of dough and place on lined cookie sheets, leaving space between them for them to spread. I only do 12 per cookie sheet, less if using a smaller sized sheet. I usually flatten them a bit.
Bake at 350° for 12-15 minutes or until they don't look gooey in the center. These are better slightly under-cooked than overcooked. I recommend baking a test cookie to see how many minutes it will take for your oven.
Remove from oven and leave on the cookie sheet for a couple of minutes before moving cookies to wire racks to cool.