Preheat oven to 350℉ and line a baking sheet with silicone mat or parchment paper.
In the bowl of a stand mixer or large mixing bowl, add your butter and sugars. Beat for 1 minute on medium-high speed.
Add your peanut butter and beat for additional minute.
Mix in eggs, one at a time until fully incorporated.
Stir in vanilla. Then add your oats, baking soda, and salt. Mix at low speed until combined.
Add in the m&ms and chocolate chips. Mix until combined.
Scoop by heaping tbsp onto your cookie sheet. Bake for 11-13 minutes or until the edges start to slightly brown.
Let fully cool before storing in an airtight container for up to 5 days and enjoy!
Notes
*Inspired by Paula Deen's Monster Cookies.**I typically make these as heaping tbsp size cookies but you can absolutely make them bigger. I've done 1.5 tbsp size and 2 tbsp size. If making bigger cookies, the baking time may increase just slightly so keep an eye on them.