Preheat your oven to 350°F. Line a rimmed baking sheet with unbleached parchment paper and set it aside.

In a medium-size bowl, place the oat flour, oats, baking soda, and salt, and whisk to combine. Set the bowl aside.

In a large bowl, place the butter, peanut butter, egg and egg yolk, vanilla, and brown sugar, and mix well. Add the oat flour mixture to the large bowl, and mix until just combined.

Add the chocolate chips and M&Ms candies and mix until the pieces are evenly distributed throughout the dough. The dough will be thick but should not be stiff.

Using a spring-loaded ice cream scoop or two spoons and scoop the dough into mounds about 2 1/2 tablespoons each onto the prepared baking sheet, about 2 inches apart from one another.

Using wet fingers, press each mound down into a disk about 1/2-inch thick.

Place the baking sheet in the preheated oven and bake for 12 to 14 minutes, or until the cookies are lightly brown around the edges, set in the center and the top of each cookie has taken on a crackled appearance.

Allow the cookies to sit on the baking sheet for 10 minutes or until set. Serve slightly warm or at room temperature.

These cookies also freeze amazingly well in a sealed freezer-safe container.