Preheat your oven to 350ºF and grease a 9x13-inch baking dish with cooking spray.

In a large bowl, mix together oats, peanut butter, maple syrup, melted butter, eggs, brown sugar, and baking soda until well combined. The mixture should resemble thick cookie dough.

Add in the M&M’s and chocolate chips, and mix again until they are evenly distributed.

Transfer the dough into the prepared baking dish and press it firmly using a wooden spoon or your hands.

Bake at 350ºF for about 17-20 minutes, or until the edges turn golden brown and the bars feel firm to the touch.

Allow the monster bars to cool for at least 30 minutes to 1 hour before slicing and serving.