Heat oven to 350°F. Line a 13x9-inch baking dish with parchment paper. Do not use foil for this recipe. If you don't have parchment paper to easily remove bars from pan after baking then proceed with an ungreased baking pan.
In large bowl fit with a mixer, beat base ingredients on low speed until dough comes together. Press mixture evenly in bottom of a 13x9-inch pan. Bake 20 to 30 minutes or until light golden brown.
In medium bowl whisk eggs. Beat in filling ingredients; granulated sugar, flour, baking powder, and lemon zest. Beat in 1/4 cup lemon juice.
Remove partially baked base from oven. Pour filling evenly over warm base.
Return to oven; bake 25 to 30 minutes longer or until top is light golden brown. If top starts to get too brown, cover with foil and continue to bake until center has settled. Cool completely, about 1 hour.
In a small bowl, combine powdered confectioners' sugar and lemon juice or water. Evenly spread glaze over the top of the cooled bar.
Refrigerate until center is set then cut into bars.