These decadent dark chocolate monster cookies are full of chocolate peanut butter, oats, chocolate chips, and M&M's. They're easy to make and bake up extra soft with LOTS of gooey chocolate!
In a large mixing bowl or the bowl of a stand mixer, beat together the butter, peanut butter, sugars and vanilla extract. Add the egg and egg yolk, mix just until combined.
In a medium mixing bowl, whisk together the oats, flour, cocoa powder, baking soda, and salt. Gradually add the dry ingredients to the wet ingredients. Mix until a soft dough forms. Fold in the M&Ms and chocolate chips with a spatula.
Place the dough in an air-tight container and refrigerate for at least 30 minutes.
Meanwhile preheat oven to 350 degrees, line baking sheets with parchment paper or baking mats. Using a standard size cookie scoop (#40 or 1.5 tbsp.) scoop balls of dough and place onto prepared sheets. Place in the oven and bake for 9-11 minutes, taking care not to over-bake. The cookies will look soft, but allow them to cool on the sheets for 5 minutes before transferring them to a wire rack to cool completely.
Notes
-You can easily mix in peanut butter chocolate chips, chunks of chopped chocolate or peanut butter cups!