Preheat oven to 325 degrees F (160 degrees C). Grease and line an 8x8-inch baking pan.
Mix the M&M's® Milk Chocolate Candy (1/2 cup) or your choice of candies and add a tablespoon of the flour to them. Mix them well and set aside. This ensures that the candies are evenly distributed and don't sink to the bottom.
Mix together Brown Sugar (1/2 cup), Vegetable Oil (1/4 cup), Plain Yogurt (1/3 cup), and Butterscotch Extract (1 teaspoon) until sugar is dissolved.
Sift in All-Purpose Flour (1 cup), Baking Powder (1/2 teaspoon), Baking Soda (1/4 teaspoon), and Salt (1 pinch). Mix together until you have a smooth batter.
Add the Cookies (1/4 cup) and M&M's® Milk Chocolate Candy (1/2 cup) to the batter.
Pour the batter onto the prepared baking pan. Top off with more candies and cookies, if desired.
Bake for 30 minutes.
Let them cool completely. Slice and serve.