Preheat your oven to 350°F/175°C. Grease and line a baking pan with parchment paper for easy removal.
Brown 1½ sticks (170 grams) of butter, this step is key! Melt it in a pan over medium heat, stirring constantly, until the bubbles disappear, and the butter turns golden brown and smells nutty. Remove it from the heat, transfer it to the mixing bowl, and let it cool slightly.
Mix 1¼ cups (250 grams) of light brown sugar, 1 tbsp of maple syrup, 1 tsp of vanilla extract, 1 egg, and 1 egg yolk in a bowl, and whisk together with the browned butter.
Add the 1½ cups of flour, baking powder, and salt, to the same bowl as the wet ingredients.
Gently mix everything together, and stir until just combined. Don’t overmix!
Fold in your flavor boosters, I used chocolate chips, but you can mix in nuts, dried fruit, or even white chocolate chunks.
Spread the batter into your prepared pan and smooth it out evenly.
Bake for 25 - 30 minutes, you want the edges golden and the center just set.
Put the baking pan on a wire rack and let it cool before slicing. (If you can wait, that is!