Beat butter and sugar together until the mixture is light and fluffy. Stir in 1/2 cup flour, the ground almonds, and cinnamon. Mix in remaining flour 1/2 cup at a time until the mixture becomes a slightly stiff dough.
Shape the dough into a ball; divide it in half. Wrap both halves in wax paper or plastic wrap, and refrigerate for about one hour.
Preheat oven to 325 degrees F (165 degrees C). Line a baking sheet with parchment paper.
On a lightly floured surface, roll half of the dough into a sheet 1/8 inch thick. With a 2 1/2-inch cookie cutter, cut as many circles from the sheet as you can. Knead the leftover scraps of dough into a ball and roll it out again into a 1/8 inch sheet. Cut out more circles. You should now have about 12 circles.
Arrange cookies on prepared baking sheet, leaving about 1 inch of space between them. Refrigerate while working with remaining dough.
Repeat the rolling and cutting process with the other half of the dough, but after placing the second batch on the baking sheet, cut out the center of each circle with a 1/2 inch cookie cutter.
Bake cookies in preheated oven until light brown, 10 to 15 minutes. Cool on wire rack for 20 minutes.
Spread a thin coating of jam on each of the cookie rounds. Set a cutout cookie on top of each, pressing the two together so they make a sandwich. Spoon a dab of jam into the opening of each tart and sprinkle the tops with confectioners' sugar before serving.
