Ingredients:

  • 280g all-purpose flour (2 1/4 cups)
  • 10g cornstarch (1 tbsp)
  • 1 tsp baking soda
  • 0.5 tsp fine grain sea salt
  • 170g unsalted butter (3/4 cup), cool soft
  • 150g dark brown sugar (3/4 cup packed)
  • 100g granulated white sugar (1/2 cup)
  • 1 large egg, room temperature
  • 1 large egg yolk
  • 1 tbsp pure vanilla extract
  • 1 cup milk chocolate M&Ms
  • 0.5 cup semi-sweet chocolate chips

Instructions:

  1. In a stand mixer or using a hand mixer, beat the cool, softened butter with dark brown sugar and granulated sugar on medium-high speed for 3 minutes until the mixture is pale and aerated.
  2. Add the whole egg, the additional egg yolk, and the vanilla extract. Beat for another 60 seconds until the mixture forms thick, velvety ribbons.
  3. Turn the mixer to the lowest setting. Gradually add the flour, cornstarch, baking soda, and salt, mixing until only a few streaks of flour remain.
  4. Gently fold in the M&Ms and semi-sweet chocolate chips using a silicone spatula.
  5. Cover the dough and chill in the refrigerator for at least 60 minutes. This prevents the cookies from spreading too thin and develops the flavor.
  6. Preheat oven to 350°F (175°C). Scoop large rounds of dough onto parchment-lined baking sheets and bake for 10 minutes until the edges are just set but the centers remain soft.