Place the flour and butter into a food processor bowl with a dough blade; process until the mixture resembles breadcrumbs. Add the sugar, eggs and extract; mix until a ball of dough is formed. Divide into two equal balls, wrap in clingfilm and chill for 1 hour.
On a lightly floured surface, roll the balls of dough to approx. 5mm thick. Stamp out two cookies in each size, dipping the cutters in flour before each use to prevent sticking.
Arrange on baking trays; bake for 10-12 minutes until firm and golden. Leave on the baking trays for 10 minutes then transfer to a wire rack to cool completely.
On a surface lightly dusted with icing sugar, roll the icing to approx. 5mm thick. Use the cookie cutters to stamp out two stars in each size.
Brush each cookie with a little jam; top with an icing star. Leave the iced cookies on a rack for a few hours or until the icing has dried.
Stack your tree starting with the largest cookies at the bottom and smallest at the top. When you get to the top, roll a small ball of icing and use it to prop up the final star. Dust with icing sugar and decorate with silver balls.