Instructions

• Preheat oven to 350°F. Line a 9x13-inch baking pan with aluminum foil or parchment paper, leaving an overhang on two sides to lift the bars out after baking.
• In a large bowl, use an electric mixer to beat the softened salted butter, packed brown sugar, and granulated sugar together until creamy and well combined.
• Add the eggs one at a time, beating briefly after each addition, then beat in the vanilla extract until incorporated.
• In a separate bowl, whisk together the all-purpose flour, baking powder, and salt.
• Add half of the flour mixture to the wet ingredients and beat on medium-low speed until just combined.
• Add the remaining flour mixture and beat on medium-low speed until the dough is just combined and no large streaks of flour remain. Do not overmix.
• Stir or fold in the semi-sweet or milk chocolate chips and the toffee bits until evenly distributed.
• Transfer the batter to the prepared 9x13 pan and spread it into an even layer.
• Bake for 26 to 30 minutes, or until the top is golden brown and a toothpick inserted near the center comes out with a few moist crumbs (not wet batter).
• Remove the pan from the oven and let the bars cool completely in the pan on a wire rack. Use the foil or parchment overhang to lift the bars out, then slice into squares.