Ingredients
Cooking spray
1 1/2 c. (320 g.) packed light brown sugar
1 c. (2 sticks) unsalted butter, melted
2 large eggs
2 tsp. pure vanilla extract
1/2 tsp. baking soda
1/2 tsp. kosher salt
2 c. (240 g.) all-purpose flour
1 c. (170 g.) semisweet chocolate chips
1 c. (180 g.) M&M’s
Preparation
Step 1Preheat oven to 350°. Thoroughly coat a 13"-by-9" baking dish with cooking spray. Fold a 16" sheet of parchment lengthwise to fit along bottom and sides of baking dish, leaving some overhang at the handles. Spray with cooking spray.Step 2In a large bowl, whisk brown sugar and butter until sugar is dissolved. Whisk in eggs one at a time until incorporated, then whisk in vanilla, baking soda, and salt.Step 3Using a flexible spatula, fold in flour, chips, and M&M’s until just combined.Step 4Transfer dough to prepared dish and smooth in an even layer.Step 5Bake bar until a tester inserted into the center comes out clean, 35 to 40 minutes. Let cool in baking dish 1 hour. Using parchment overhang, lift bar onto a cutting board. Slice into 12 bars. Step 6Make Ahead: Bars can be made 1 week ahead. Store in an airtight container at room temperature.
Looking for variations? Mix in some mini peanut butter cups for part of the M&M’s. Or give the bars monster cookie energy with pretzels, peanuts, and oats. For all the precision bakers out there, make sure to trim 1/4" off the edges of the cooled block before cutting into bars. That will ensure sharp, clean lines all around. (And extra snacks for the chef.) For everyone else, just cut in and enjoy immediately! Store the bars in an airtight container for up to 1 week or freeze for up to 3 months.
