Ingredients:

  • 1/2 cup (1 stick) unsalted butter, melted and cooled
  • 1 cup (200 g) light brown sugar, packed
  • 1/2 cup (100 g) granulated sugar
  • 2 large eggs, room temperature
  • 1 teaspoon vanilla extract
  • 1 3/4 cups (210 g) all-purpose flour
  • 1 teaspoon baking soda
  • 1/2 teaspoon fine sea salt
  • 1 1/2 cups (250 g) milk chocolate M&M’s (reserve 1/4 cup for topping)

Instructions:

  1. Preheat oven to 350°F / 175°C. Line the 9x9 inch pan with parchment paper, allowing the edges to overhang on two sides (this creates handles for lifting). Lightly grease the exposed pan sides if desired.
  2. In a medium bowl, whisk together the flour, baking soda, and salt until thoroughly combined. Set aside.
  3. Pour the cooled, melted butter into the large mixing bowl. Add the brown sugar and granulated sugar. Whisk vigorously for about 1 minute until the mixture is smooth and glossy.
  4. Beat in the eggs one at a time, ensuring the first is fully incorporated before adding the second. Stir in the vanilla extract. The mixture should look thick and cohesive.
  5. Gradually add the dry flour mixture to the wet mixture. Use a rubber spatula to fold the ingredients together until just combined. Stop mixing the moment you no longer see streaks of dry flour.
  6. Gently fold in 1 1/4 cups (210g) of the M&M’s.
  7. Scrape the dough into the prepared baking pan. Press the dough evenly into the corners and smooth the top. Sprinkle the reserved 1/4 cup (40g) of M&M’s evenly over the surface.
  8. Bake for 30–35 minutes. The edges should be set and golden brown, and the centre should look slightly underbaked but set. A toothpick inserted into the centre should come out with moist crumbs attached.
  9. Remove the pan from the oven and place it on a wire rack. Crucially, allow the bars to cool completely in the pan—about 60 minutes—before using the parchment paper handles to lift the bar out and cut into squares.