Ingredients:

  • 1 cup unsalted butter, softened (227g)
  • 1 cup granulated white sugar (200g)
  • 0.5 cup light brown sugar (100g)
  • 2 large eggs, room temperature
  • 1 tablespoon pure vanilla extract
  • 2.5 cups all-purpose flour (312g)
  • 1 teaspoon cornstarch
  • 1 teaspoon baking powder
  • 0.5 teaspoon salt
  • 1.5 cups M&M's milk chocolate candies, divided (approx. 260g)

Instructions:

  1. Preheat your oven to 350°F (175°C). Line a 9x13 inch baking pan with parchment paper, ensuring there is an overhang on the sides for easy removal.
  2. In a large mixing bowl or stand mixer, cream together the softened butter, granulated sugar, and light brown sugar until the mixture is light, fluffy, and pale (about 2-3 minutes).
  3. Beat in the eggs one at a time, followed by the vanilla extract. Scrape down the sides of the bowl to ensure a smooth emulsion.
  4. In a separate medium bowl, whisk together the all-purpose flour, cornstarch, baking powder, and salt.
  5. Gradually add the dry ingredients to the wet mixture. Mix on low speed until just combined, being careful not to overmix.
  6. Gently fold in 1 cup of the M&Ms using a rubber spatula.
  7. Press the dough evenly into the prepared 9x13 pan. Scatter the remaining 0.5 cup of M&Ms over the top, pressing them down slightly.
  8. Bake for 22-26 minutes until the edges are light golden brown and the center is just set but still soft.
  9. Allow the bars to cool completely in the pan before lifting them out using the parchment paper and slicing into 24 squares.