Preheat your oven to 350°F (175°C). Grease or line a 9×13-inch baking dish with parchment paper.

In a saucepan over medium heat, melt the softened butter until it starts to bubble slightly. Remove from heat.

In a large mixing bowl, combine the melted butter and brown sugar, stirring until well combined and glossy.

Mix in the eggs one at a time, ensuring each is fully incorporated before adding the next. Stir in the vanilla extract.

In a separate bowl, whisk together the flour, baking powder, baking soda, ground cinnamon, cayenne pepper, and salt. Gradually add this to the wet mixture, mixing just until combined.

Spread the batter evenly into the prepared baking dish and sprinkle the granulated sugar over the surface.

Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted comes out clean with a few moist crumbs.

Let the blondies cool in the pan for about 10 minutes before transferring them to a wire rack to cool completely.