In a separate bowl, whisk together flour, salt and baking powder; add to the peanut butter mixture and mix well.
Divide the dough into 4 equal portions. Wrap each portion in plastic wrap or waxed paper and refrigerate 2 hours or overnight.
Remove portions from refrigerator and place each portion between 2 sheets of plastic wrap or waxed paper. Roll each portion into a 'sheet' about 1/8-inch thick. (Refrigerate dough again if it becomes too soft to handle).
Preheat oven to 350 degrees. Using a drinking glass or cookie cutter, cut dough into circles. Using a smaller drinking glass or cookie cutter, cut smaller circles or 'windows' in half the circles. Transfer cookies to non-stick baking sheet, leaving 1/2 inch between them.
Bake all cookies 5 to 6 minutes or until they're just starting to brown. Using a spatula, transfer the cookies to a cooling rack. When cookies have cooled, spread jelly on the plain cookie and top with the ''window'' cookies.