Cream together the butter and the sugar until light and fluffy.
Beat in the egg & vanilla. Then use a wooden spoon to mix in the flour and baking powder.
The dough will turn out looking like dry sand at first. Use your hands to knead the dough until it sticks together in one brick.
Flour a slick surface and use a rolling pin to roll out the dough. Use two different cookie cutters to cut out the top and bottom cookies from the dough. On the "tops", use another cookie cutter to cut out a center shape so that you can see the jam through the dough.
Line a baking tray with aluminum foil and bake the cookies for about 14 minutes. I liked mine to be just turning yellow on the bottom.
Remove the cookies from the tray. As the tops cool, put powdered sugar in a sifter and sprinkle sugar over the tops of the cookies.
Put the jam in a pot on the stove and heat until it just begins to boil.
Once the jam has begun to cool, spread an equal amount on each cookie "bottom". Place the "top" over the jam, and allow to cook completely before enjoying.