Line 2-3 baking sheets with parchment and then set aside.
In a large mixing bowl, combine the butter, and peanut butter - beat until smooth.
Add the granulated sugar, brown sugar, eggs and vanilla - beat until blended.
Next add the oats, flour, baking powder, baking soda and salt. Stir until just blended.
Fold in both types of M&M's and the chocolate chips.
Scoop out the dough and roll between your hands to form into balls - about the size of a golf ball.
Place on the prepared baking sheets about 2" apart.
Bake for 12-13 minutes or until golden brown.
Remove from the oven and immediately add additional M&M"s and chocolate chips as desired.
Transfer to a wire rack to cool completely before storing in an airtight container.
Halloween Monster Cookie
When making the Halloween version - swap out the M&M's and replace the chocolate chips with the candy corn.
Add the eyes and additional candy corn after baking.
Notes
I’m using Halloween-colored M&Ms, but feel free to use any add-ins you like.
If you add candy corn to the cookie dough, make sure they are fully encased in the dough when you bake them or they’ll melt in the oven. I recommend adding them on top of the cookies if you want to keep the shape.
Candy eyes add a fun Halloween twist as well, but they are completely optional! Just make sure to press them into the cookies while they’re still warm so they stick