01 -
Cut butter into cubes and place in a heavy saucepan over medium heat. Stir constantly as the butter melts and begins to foam. Continue stirring until the butter turns golden brown and develops a nutty aroma. Immediately remove from heat and transfer to a heat-safe bowl to cool.
02 -
While the brown butter cools, sift together the flour, cinnamon, and baking soda in a medium bowl.
03 -
Preheat oven to 350°F (175°C). Line a 9×9 inch baking pan with parchment paper, leaving extra paper hanging over the sides to create handles for easy removal. Lightly spray with non-stick cooking spray.
04 -
In a large bowl, combine the cooled brown butter, mashed banana, brown sugar, granulated sugar, eggs, and vanilla extract. Whisk until well combined and smooth.
05 -
Add the sifted dry ingredients to the wet ingredients. Fold together gently with a spatula until just combined, being careful not to overmix.
06 -
Gently fold in the semi-sweet chocolate chips, milk chocolate chips, and toffee bits until evenly distributed throughout the dough.
07 -
Spread the cookie dough evenly into the prepared baking pan, smoothing the top with a spatula.
08 -
Sprinkle additional chocolate chips and toffee bits over the top of the dough, gently pressing them in slightly.
09 -
Bake for 30-35 minutes, until the top is golden brown and the center is mostly set but still slightly soft. The edges will be more firm than the center.
10 -
While the bars are still warm (but not hot), sprinkle more chocolate chips and toffee bits on top, allowing them to soften slightly from the residual heat.
11 -
Allow the cookie bars to cool completely in the pan. This is important for the bars to set properly and achieve the right texture.
12 -
Once completely cooled, use the parchment paper handles to lift the bars out of the pan. Cut into 9 equal squares and serve.