Preheat oven to 350 degrees and line a 9x13-inch baking pan with aluminum foil or parchment paper.
Use an electric mixer to beat butter, brown sugar, and granulated sugar until creamy.
Beat in the eggs and vanilla extract.
Combine the flour, baking powder, and salt.
Add half the flour mixture to the mixing bowl and beat on medium-low until mixed in.
Beat in remaining flour.
Stir in chocolate chips and toffee bits.
Transfer batter to prepared pan. Bake for 26 to 30 minutes or until golden brown on top.
Let cool before slicing.
Notes
Unsalted butter can be used. Change the salt amount to 1/2 teaspoon.Leftovers can be stored in an airtight container or ziptop bag for 4 to 5 days. Can be frozen for up to 2 months.