Preheat the oven to 350 degrees F (175 degrees C).
To make the crust: Blend 2 cups flour, softened butter, and ½ cup sugar in a medium bowl until well combined; press into the bottom of an ungreased 9x13-inch pan.
Bake in the preheated oven until firm and golden, about 15 minutes. Meanwhile, make the filling: Whisk remaining 1 ½ cups sugar and ¼ cup flour in a medium bowl. Whisk in eggs, then lemon juice until smooth; pour filling over the baked crust.
Bake in the preheated oven for 20 minutes. Set the pan aside to cool completely; the bars will firm up as they cool. When cooled, cut into uniform squares.
