With the electric mixer using the paddle attachment or in the food processor with a steel blade, mix the flour, butter and sugar.
Add the egg and mix for 3 minutes to form a dough ball.
Remove from the mixer and roll into a ball. Wrap in plastic and chill for at least 1/2 hour.
Roll out the chilled dough to 1/8" thick and cut into desired shapes, making sure to make a hole in the middle of each shape.
With a metal spatula, transfer to baking sheets.
Preheat oven to 325 °F.
Bake in the preheated oven until golden, not brown, about 10 to 12 minutes.
Transfer to cooling rack.
Repeat process until all of the dough has been used.
Sandwich the cookies by spreading jam on the top of one cookie and covering it with another.
Using a small mesh strainer, sift powdered sugar over the tops of the cookies.
Makes about 60 small cookies.
Note: the plain cookies freeze well. Remove from freezer and finish with filling and sugar topping. Cookies will keep in an airtight container for a week.