Ingredients
Equipment
Method
- Heat the oven to 350°F.
- Line a large baking sheet with parchment paper.
- Beat the butter, brown sugar, and granulated sugar with a mixer on medium speed until creamy, about 2 minutes.
- Beat in the egg, egg yolk, and vanilla until combined.
- Whisk together the flour, cornstarch, baking soda, and salt in a separate bowl.
- Add the dry ingredients to the butter mixture and mix on low just until no dry flour remains.
- Fold in the mini M&M's and mini chocolate chips.
- Cover the dough and chill for 1 hour.
- Scoop the dough into 2-tablespoon portions and arrange them about 2 inches apart on the prepared baking sheet.
- Bake at 350°F for 9 to 11 minutes, until the edges are lightly set and the centers still look slightly underbaked.
- Repeat in batches, letting the baking sheet cool completely between batches.
- Let the cookies cool on the baking sheet for 5 minutes.
- Transfer the cookies to a wire rack to cool.
Notes
For soft centers, take the cookies out when the edges are lightly set and the centers still look slightly underbaked. Store in an airtight container in the refrigerator for up to 5 days; freeze baked cookies for up to 2 months. For a dairy-free variation, use dairy-free butter, candy-coated chocolates, and chocolate chips.
