Brown Butter Christmas M&M Cookie Bars

Bahan-bahan (22 porsi)

• 2 sticks (1 cup) salted butter
• 3/4 cup packed dark brown sugar
• 1/4 cup granulated sugar
• 2 large eggs, at room temperature
• 1 tablespoon vanilla extract
• 2 1/4 cups all-purpose flour
• 3/4 teaspoon baking soda
• 1/2 teaspoon kosher salt
• 1 cup semi-sweet chocolate chips
• 1 cup Christmas M&M's...or more!
• 10 -12 Hershey's Milk chocolate kisses, halved
• flaky sea salt, for sprinkling