Preheat the oven to 350 degrees.

Grease a 9x13 baking pan and then line it with parchment. Set aside.

Combine the butter and sugar in the mixing bowl. Beat well until light and fluffy.

Beat in the eggs, one at a time.

Add the lemon zest, lemon juice, and vanilla extract, mixing until just combined.

Keeping the mixer stirring on low, gradually add the flour, baking powder, and salt. Stir until just combined.

Spread the mixture into the prepared pan in a smooth, even layer.

Bake for 20-25 minutes or until the edges are golden brown. A toothpick test should return clean.

Let the bars cool in the pan on a wire rack while you make the glaze.

To make the glaze, whisk the confectioner’s sugar with the lemon juice and lemon zest until combined and the mixture is smooth.

Once the bars have cooled to room temperature, pour the glaze over the top. Allow to the glaze to set before cutting the bars and serving.

If you want the process to move a little faster, you can cool the bars in the refrigerator (make sure to set them on a hot pad) and then chill them again once you add the glaze. Remove and bring them to room temperature before slicing and serving.