Start by browning the butter. In a small saucepan, melt the butter over medium heat, stirring frequently. Keep an eye on it as it foams and starts to turn a golden brown color. You’ll know it’s ready when it smells nutty and has a rich amber hue. Remove from heat and let it cool slightly.
In a mixing bowl, combine the warm brown butter and brown sugar. Whisk until smooth. Add in the egg and whisk until fully incorporated.
In another bowl, whisk together the flour, baking powder, and cinnamon. Gradually add this dry mixture to the wet ingredients, stirring gently until just combined. Be careful not to overmix!
Gently fold in the chocolate chips and toasted walnuts. The mixture should be thick and rich.
Preheat your oven to 350°F (175°C). Line your baking pan with parchment paper, leaving some overhang for easy lifting later. Spread the blondie batter evenly in the pan. Sprinkle flaky sea salt on top for that perfect contrast. Bake for 20-25 minutes, or until the edges are golden and a toothpick inserted into the center comes out with a few moist crumbs.
Allow the blondies to cool in the pan for about 10 minutes before lifting them out using the parchment paper. Let them cool completely on a wire rack before cutting into squares.
