Sift together flour, baking powder and salt. In a separate bowl, cream together butter and sugar until light and fluffy. Add eggs one at a time and beat in between additions, until smooth.
Beat in the dry ingredients until a dough starts to form. Transfer to a clean surface, lightly dusted with flour. Bring the dough together with your hands.
Cut in half and shape into two rectangles. Cover each with plastic wrap and refrigerate for 30 minutes.
Preheat oven to 160°C (or 140°C fan forced). Line two large baking trays with baking paper.
After 30 minutes of resting, remove dough from fridge and using a rolling pin, roll each rectangle flat until it is 5mm thick. Using cookie cutters, cut as many shapes as you can. Using a smaller cookie cutter, cut a small window in the centre of half the cookies.
Roll up remaining dough and repeat the process until there is none left.
Divide shapes amongst baking trays and bake for 8-12 minutes, or until light golden brown.
Let cookies cool on baking trays for at least 30 minutes.
Spread your favourite jam onto the centre of all the bottom cookies and sandwich with the top (window) cookies. Dust with icing sugar and serve.