Preheat over to 375F. Grease 2 cookie sheets. Set aside.
Put all cookie ingredients in large bowl. Beat together with electric mixer until just incorporated. Batter Will be very thick.
Drop batter by heaping tablespoons into 12 evenly distributed mounds on the first greased cookie sheet. Place in oven for 10-12 minutes. While in oven fill second cookie sheet in same manner. You should get 24 cookies total. You can make smaller and get one more dozen for 36 total. If you must reuse the first cookie sheet let it cool before baking next batch.
When first cookies are done swap out In oven with second cookie sheet. Let first batch cool on cookie sheet for 2 minutes then carefully transfer to wire rack to finish cooling completely. Repeat with following batch(es) when done as well.
While cookies cool, place all filling ingredients in a medium bowl. Beat with an electric mixer until creamy and fluffy (it should look about doubled in size from.when.you started when whipped properly).
When cookies are completely cool, spread about one tablespoon of filling on the bottom (flat) side of one cookie. Pick a second cookie about the same shape and gently press bottom side on top of filling. Repeat until all cookies and filling are used up.
Enjoy fresh or wrap individually in plastic wrap to save for later. Place in fridge if desired (we like them cold lol).
Note: You can substitute butter for the shortening. Allow the butter to set out for about an hour to soften before use. I personally do not like margarine for this recipe (or any baked good lol), but it can be used as well.