Preheat the oven to 350 degrees F (175 degrees C). Grease a 9×9-inch baking dish. You can also line with a piece of parchment for easy removal, if desired.
Cream the Butter (1/2 cup), Chunky Peanut Butter (3 tablespoon), Brown Sugar (1/2 cup), and Vanilla Extract (1 teaspoon) together.
Add the Egg (1) and white of the other Egg (1), and mix just until incorporated.
Add the Quick Cooking Oats (1/2 cup), All-Purpose Flour (1 cup), Baking Powder (1/2 teaspoon), Ground Cinnamon (1/4 teaspoon), and mix until incorporated. Fold in the Chocolate Chunks (1/2 cup), M&M's® Milk Chocolate Candy (1/2 cup), and Peanuts (1/4 cup).
Spread evenly onto the prepared baking dish and bake in the oven for 18-20 minutes.
Let cool, then slice and serve.