1. Preheat the oven to 350°F (175°C).
2. Line an 8×8 inch baking pan with parchment paper to ensure easy removal and cleanup.
3. Whisk together granulated sugar, melted butter, and lemon zest in a large bowl until the sugar dissolves.
4. Add eggs and additional yolks into the mixture, whisking until smooth and creamy for a dense texture.
5. Gently fold in all-purpose flour, baking powder, and salt using a spatula. Avoid overmixing to maintain the correct texture.
6. Pour the batter into the prepared baking pan, spreading it evenly.
7. Bake in the preheated oven for 20 to 30 minutes, checking for doneness with a toothpick (it should come out with a few moist crumbs).
8. Allow the brownies to cool in the pan before transferring them to a wire rack.
9. Prepare a simple lemon glaze by mixing powdered sugar and fresh lemon juice.
10. Drizzle the glaze over the cooled brownies for an extra burst of citrus flavor.
11. Cut the lemon brownies into squares and serve.