To begin, preheat your oven to 350 and spray two pans with non-stick spray.

To a large mixing bowl, add your butter and brown sugar and beat together with a mixer till creamy. Add your peanut butter and beat together till well combined. Add your vanilla and egg and briefly blend in.

To the same bowl, add your oats, baking soda and salt and beat together till you have a consistent cookie dough. Add your M&M's and fold them into your dough.

Using a large cookie scoop, scoop the dough onto your pan and spread apart into two rows, with three cookies in each row. Bake in the oven for 14-16 minutes, or till the edges of the cookies are set but the center may look just a touch underdone.

Let cool entirely, then devour!