Preheat oven to 350f and line a 9X9 inch brownie pan with parchment paper.
In a bowl add melted butter, sugar, lemon zest, lemon juice, egg, and yolks. Mix to incorporate.
Add in flour, baking powder, salt. Mix until flour is fully incorporated. Batter will be thick.
Pour batter into prepared brownie pan and using back of spatula spread out batter.
Bake in oven for 35-37 minutes. Once cooked, remove from oven and allow to fully cool
In a small bowl add powdered sugar, lemon zest, and lemon juice. Drizzle glaze over cooled brownies. Cut and serve!