Reserve 2 tablespoons powdered sugar for dusting later. Place 2 cups flour, butter, and powdered sugar into a mixing bowl. Cut butter into dry ingredients with a pastry blender.
Pat crust into 9x13 pan. Crust will seem dry but it will bake up nicely. Bake for 15 minutes.
While crust is baking, place eggs, sugar, ¼ cup flour, lemon juice, and baking powder into a bowl and mix well with wire whisk or electric mixer.
When crust is finished, remove from oven and pour the filling onto the crust. Return to oven and bake for 20 minutes longer.
After lemon bars are finished baking, sprinkle with reserved powdered sugar while bars are still hot. Cool completely.