Step 1: Preheat the Oven - Begin by preheating your oven to 350°F (175°C).
Step 2: Prepare Your Baking Sheet - Line a baking sheet with parchment paper.
Step 3: Mix Dry Ingredients - In a medium bowl, whisk together the all-purpose flour, cornstarch, baking soda, and sea salt.
Step 4: Cream the Butter and Sugars - In a large mixing bowl, cream the unsalted butter, dark brown sugar, and granulated sugar together until light and fluffy.
Step 5: Add the Egg and Vanilla - Add the large egg and vanilla extract to the butter mixture and mix until fully combined.
Step 6: Combine Wet and Dry Ingredients - Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined.
Step 7: Fold in the Mix-Ins - Gently fold in the Mini M&Ms and mini chocolate chips.
Step 8: Scoop the Dough - Using a cookie scoop, portion out the cookie dough onto the prepared baking sheet.
Step 9: Bake - Bake for 10-12 minutes or until the edges are lightly golden.
Step 10: Cool and Enjoy - Allow the cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack.
