Cream the butter and sugar:
In a mixing bowl, beat the butter and sugar together until pale and creamy. Add vanilla essence and mix well.

Mix the dry ingredients:
Add the flour and salt, and mix until a soft dough forms. Divide the dough in half, flatten into discs, and wrap in cling film.

Chill the dough:
Refrigerate the dough for at least 30 minutes.

Preheat the oven:
Preheat to 180°C (350°F) and line two baking trays with baking paper.

Roll and cut shapes:
On a lightly floured surface, roll out one dough disc to about 5mm thickness. Use a star-shaped cookie cutter to cut out cookies. For half of them, use a smaller star cutter in the centre to create a “window.” Transfer to the baking trays.

Bake:
Bake for 10–12 minutes or until the edges are just golden. Cool on the tray for a few minutes, then transfer to a wire rack to cool completely.

Assemble the cookies:
Spread a small amount of jam on the whole star cookies. Gently press the “window” cookies on top to sandwich. Dust with icing sugar before serving.

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