1-First Step: Beat the softened butter, brown sugar, and white sugar together until light and fluffy, about 2-3 minutes with an electric mixer. This process creates air pockets that contribute to a lighter texture.

2-Second Step: Add the eggs one at a time, beating well after each addition. Then stir in the vanilla extract, ensuring it’s evenly distributed throughout the mixture.

3-Third Step: Mix in the peanut butter until fully combined. The batter may look slightly curdled at this stage, which is normal and will resolve when you add the dry ingredients.

4-Fourth Step: In a separate bowl, whisk together the flour (or oat flour), quick oats, baking soda, and salt. Gradually add these dry ingredients to the wet mixture, mixing on low speed just until combined.

5-Fifth Step: Fold in the chocolate chips and M&Ms by hand, being careful not to overmix which could develop too much gluten and create tough bars.

6-Sixth Step: Transfer the dough to your prepared 9×13-inch pan. Using greased hands or a spatula, press the mixture evenly into the pan, ensuring it’s uniformly thick for consistent baking or chilling.

7-Final Step: For no-bake version: Refrigerate for at least 2 hours until firm. For baked version: Bake at 350°F (175°C) for 20-25 minutes until edges are lightly golden. Cool completely before cutting.