Preheat oven to 350° F. Grease a 9x13-inch baking pan with non-stick spray. (Or you can line with foil or parchment paper for easy removal).
In a large bowl, stir flour, sugar, baking powder and salt together. (I used a whisk to stir it. It sifts the flour at the same time).
Add softened butter to flour mixture, stir with a spatula until combined.
In a medium bowl, whisk together the eggs, lemon juice and lemon zest. Pour mixture into the flour mixture. Stir with a spatula until smooth and combined. (A few lumps may remain).
Pour batter into prepared baking pan and spread out evenly. Bake 30 to 35 minutes or until a toothpick inserted in center comes out mostly clean. Remove from oven and let cool completely before glazing.
FOR LEMON GLAZE: Whisk together glaze ingredients until smooth. Pour and spread evenly over cooled brownies. Let glaze set before cutting into bars. Serve and enjoy!