Preheat your oven to 350°F (175°C). Grease a 9x13-inch baking dish or line it with parchment paper for easy removal.

In a large mixing bowl, combine the melted butter and granulated sugar. Mix until well combined.

Add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.

In a separate bowl, whisk together the flour, baking powder, and salt. Gradually add the dry ingredients to the wet mixture, stirring until just combined.

Fold in the fresh lemon juice and lemon zest until evenly distributed.

Pour the batter into the prepared baking dish and spread it evenly.

Bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean.

Allow the brownies to cool in the pan for about 10 minutes, then transfer to a wire rack to cool completely.

For the glaze, whisk together the powdered sugar, lemon juice, and lemon zest in a small bowl until smooth.

Once the brownies are completely cooled, drizzle the glaze over the top. Cut into squares and serve.