sift dry ingredients into a medium bowl and set aside.
in a large bowl, using an electric mixer on medium speed.beat the butter and powdered sugar till smooth -- about 1 minute.
stop and scrape down sides of bowl as needed during mixing --.
on low speed, mix in dry ingredients and the dough holds together and comes away from the sides of the bowl.
divide the dough in half and form into two 6" discs -- wrap each in plastic wrap and refrigerate the dough until cold -- at least 45 minutes.
preheat the oven to 325*.
Line two cookie sheets with parchment paper or lightly spray with non stick spray.
unwrap one piece of dough.lightly flour the rolling surface and rolling pin.roll the dough into a rectangle 12x8".and 1/4" thick.
slide a butter knife under it to loosen it from the rolling surface.
use a cookie cutter to cut out 3 1/2" circles or any shape you prefer --.
set dough scraps aswide.
place dough with help of thin metal spatula.cake frosting utensil works great here.
1" apart on prepared sheets -- they do not spread very much -- Repeat the rolling and cutting process with the second piece of dough. gather together all of the dough scraps, forming a smooth dish.repeat the rolling and cutting process.you will have 18 cookies when finished.
cut about 1" circle, or other shape from the center of half of the cookies.and remove these from the cookies -- you can bake these for snacks.
bake the cookies one sheet at a time until edges are light broqwn and tops are firm.about 20 minutes.
cool for 3 minutes on the sheets before transfering them to a wire rack to cool completely.
to prepare the FILLING:
in a medium bowl, using an electric mixer on medium speed, beat the butter, powdered sugar, lemon zest and lemon zest till smooth.
turn the cookies without the holes, bottom side up.leave just 1/8" plain edge, spread about 1 tblspoon filling on each one.
place the bottoms of the cookies with the holes on top of the filling.
Cookie sandwiches can be wrapped individually in plastic wrap and stored in a tightly covered container in refrigerator for up to 4 days.
bring to room temperature before serving to enhance lemon flavors.