Begin by preheating your oven to 350°F (175°C). Prepare a 9x13 inch baking dish by greasing it lightly and lining it with parchment paper, leaving some overhang on the sides for easy removal later.
In a medium-sized saucepan, place the unsalted butter over medium heat. Stir frequently, allowing the butter to melt completely. Continue cooking and whisking for about 5-7 minutes until the butter turns a deep golden brown and releases a nutty aroma. Once browned, remove from heat and let it cool for a few minutes.
In a large mixing bowl, combine the browned butter with the packed brown sugar and granulated sugar. Whisk the mixture vigorously until it is completely combined and smooth in texture.
Add the eggs to the bowl, introducing them one at a time. Beat the mixture well after each addition to ensure it is thoroughly incorporated. Stir in the vanilla extract for added flavor.
In a separate bowl, whisk together the dry ingredients: the all-purpose flour, baking powder, baking soda, cream of tartar, salt, and 1 teaspoon of cinnamon, ensuring there are no clumps.
Gradually fold the dry ingredients into the wet ingredients, mixing until just incorporated. Be cautious to avoid overmixing, as this can affect the texture.
Transfer the batter to the prepared baking dish, spreading it out evenly with a spatula to smooth the top.
In a small bowl, combine the remaining 1/4 cup granulated sugar with the additional 1 teaspoon of cinnamon. Evenly sprinkle this cinnamon-sugar mixture over the top of the blondie batter for a delightful crust.
Bake in the preheated oven for 20-25 minutes. Check for doneness by inserting a toothpick into the center; it should come out clean or with a few moist crumbs clinging to it. The edges should be lightly golden brown.
Once baked, remove the blondies from the oven and allow them to cool in the pan for about 10 minutes. Use the parchment overhang to lift them out of the pan, and transfer to a wire rack to cool completely.
After cooling, cut the blondies into squares to serve and enjoy!
Notes
Serve on a decorative platter and consider garnishing with powdered sugar or additional cinnamon.
Keyword blondies, brown butter, dessert, snickerdoodle