Sift the flour and custard powder into a bowl and set aside.

In another bowl, mix the butter and icing sugar until it’s well combined, then add in powdered milk and mix again.

Add in 1 large egg yolk, vanilla extract and mix again just until well combined.

Gradually add in the flour, mixing until it’s combined each time.

Using your hands form the dough into a ball, break into 3 or 4 small parts.

Sprinkle some flour on the work surface. Work with one part of dough, wrap the rest in clingfilm and set aside.

Using your hands or a rolling pin, form the dough into a disk at about 5mm thickness and about 5 cm diameter, if the dough is a bit soft and sticky, add more flour if needed. (Note: If the dough is too soft, place it in the fridge for 5 minutes, but not too long as it may get too hard and break when you roll it)

Place a round ball of pineapple jam filling into the dough and carefully wrap the filling until fully covered. Roll the dough gently into a ball and press it slightly. Make light criss cross marks on the top of the ball and place onto a lined baking tray.

Gently brush each pineapple tart with egg wash. Bake at 180ºC in a preheated oven for 20-25 minutes, or until they are golden brown and they're fully cooked. Allow them to cool completely on a rack, before storing in an airtight container.