Place the room temperature butter and the sugar into the Thermomix bowl. Mix for 15 seconds, Speed 4. Scrape down the sides of the bowl. Mix for a further 15 seconds or until pale and creamy.
Add the egg and vanilla extract and mix for 30 seconds, Speed 3.
Add the plain flour and bi-carbonate of soda and mix for 10 seconds, Speed 5. Then knead for 2 minutes, Kneading function.
Place the Thermomix bowl with the dough inside, into the fridge for 30 minutes to chill.
Once chilled, form the dough into a ball. Place the ball onto a lightly floured board or bench and roll it out with a rolling pin until 5mm thick.
Use a 6cm diameter round cookie cutter to cut out the pastry circles.
Lightly grease a 12 hole patty pan tin. Gently press each of the pastry circles into the holes.
Spoon 1-2 teaspoons of jam into the pastry shells, filling almost to the top.
Preheat oven to 160 degrees celsius (fan-forced).
Optional (but recommended - see notes): Chill the pastry in the patty pan tin in the freezer for 30 minutes.
Bake the tarts for 10 minutes or until the edges of the pastry start to turn slightly golden.
Allow the tarts to cool in the baking pan for 30 minutes before transferring to a wire rack to cool completely. Note: as tempting as it is, do NOT eat the tarts while they are warm as the jam will burn your mouth.
Store in an airtight container in the fridge for 3 days.