Preheat oven to 350 degrees F. Line the bottom of an 8'' pan with parchment paper, or grease with cooking spray and set aside
For the crust: In a mixing bowl or the bowl of a stand mixer, cream together the butter and powdered sugar. Add the flour and salt and mix on low speed, just until combined.
Press the dough evenly into the bottom of the prepared dish. Bake for 10 minutes. Remove from oven and set aside.
While the crust cools, make the lemon filling.
Mix the lemon zest and sugar in a mixing bowl. Add the lemon juice, flour, baking powder, and eggs. Mix until well combined and the sugar is dissolved. Pour mixture over crust.
Bake at 350 degrees for 20-30 more minutes, or until the filling has set. Remove from oven and allow to cool completely.
Sprinkle with powdered sugar before cutting and serving. Store lemon bars in the refrigerator.
Make ahead instructions: Make lemon bars up to 2 days in advance. Allow to cool completely before covering and storing in the refrigerator.Freezing instructions: Allow lemon bars to cool completely and cut into squares. Store in an even layer in a freezer safe container or bag for up to 2 months.