Preheat oven to 350 and line baking sheets with parchment paper or a silicone mat.
Combine the peanut butter, brown sugar, sugar, and butter in a large bowl and beat until well combined.
Mix in vanilla and eggs until combined.
Mix in the oats and baking soda until combined.
Add chocolate chips and M&Ms and stir into the cookie dough by hand.
Drop 2 tablespoons of dough onto sheets using a cookie scoop and, if desired, add a few extra M&Ms on top.
Bake for 10 minutes then cool for 5 minutes on the pan before transferring to a wire rack to cool completely. Store in airtight container.
Notes
The cookies won’t appear done after 10 minutes, but they are and will set up nicely. You don’t want to overbake them!You can substitute 1/2 cup Biscoff cookie spread for 1/2 cup of peanut butter if you want to change up the flavor.