Preheat the oven:
Preheat the oven to 180°C (160°C fan-forced) / 350°F. Prepare 2x 12-hole non-stick patty pan or regular muffin pans.

Cream the butter and sugar:
In a mixing bowl, cream together the sugar and butter until pale and creamy. Use an electric mixer for about 1-2 minutes, scraping down the sides occasionally.

Add egg and vanilla:
Beat in the egg and vanilla extract until just combined. The mixture doesn’t need to be smooth.

Add the flour:
Mix in half the flour on the lowest mixer setting until just combined, then repeat with the remaining flour. The dough should start to clump together.

Roll out the dough:
Place the dough on a lightly floured surface. Sprinkle some flour on top, then roll it out to about 4mm thick (⅙ inch). The dough is delicate, so handle it gently and make sure it moves freely on the surface.

Cut the dough:
Use a 6 ½ cm (2 ½ inch) round fluted cookie cutter to cut out circles. Re-roll the dough as needed, shaking off excess flour before re-rolling.

Place dough in pan:
Carefully place the dough circles into the muffin pan holes, gently pressing down to shape the tart shells.

Chill the dough:
Chill the tart shells in the pan for 30 minutes before baking (or up to 2 days if covered with plastic wrap).

Fill and bake:
Fill each tart shell with 2-3 teaspoons of jam or curd. Bake for 10-12 minutes until the edges are golden. Let cool for at least 30 minutes before transferring them to a cooling rack to cool completely.