Preheat oven to 350 degrees. Using a stand mixer with a paddle attachment, cream the butter for 2 minutes until light in color. Add the powdered sugar and mix for another minute.
Mix the flour, polenta and salt in a bowl and add it to the butter mixture. Mix just until dough comes together.
Separate dough into 2 disks. Cover in plastic wrap and chill for 30 minutes.
Once chilled, dust a large counter space with flour and roll the dough out about 1/4 in thick. Cut dough into small rounds using a cookie cutter.
Lay cookies on a sheet pan lined with parchment paper and bake at 350 degrees for 8 to 10 minutes just till golden brown. Let cookies chill.
Lemon Curd Cream
Place eggs, yolks, lemon juice, lemon zest and sugar in a bowl that fits over a pot of water.
Bring a pot of water to a simmer and place the bowl over the pot create a double boiler. Whisk the mixture continuously until everything comes together and thickens. About 5 to 10 minutes.
Once thickened immediately strain curd into another bowl then whisk in butter until smooth.
Place the lemon curd mixture in the refrigerator and chill until completely cold.
Whip the cream and powdered sugar to stiff peaks then fold it in the lemon curd. Place in a piping bag.
To assemble, place half of the cookies turned over and pipe about a tablespoon of filling on each cookie. Then sandwich it with another cookie. Place sandwiched cookies into the freezer for 2 hours to set.
When ready to serve sift more powdered sugar on top of cookies and enjoy.