Using a wooden spoon or an electric mixer with paddle attachment, beat butter, condensed milk, egg yolk and vanilla for about 1-2 mins or until combined.

Sift flour, cornflour and salt into the butter mixture. Use a spoon or spatula to mix until all are well incorporated. Transfer mixture onto a plastic wrap and use the wrap to knead until mixture forms a soft pliable dough. Wrap dough with plastic wrap and allow it to rest at room temperature for about 30 mins. Do not chill the dough.

Roll pineapple filling (about 8g) and divided pastry dough (about 10g) into balls.

Flatten a piece of dough and place a piece of the roll pineapple filling in the middle. Bring the edges of the dough together and press lightly to seal. Roll it in between your palms to shape it into a ball. Decorate the pastry with a pincher if desired.

Arrange the tarts on the prepared trays. Use a fine brush to brush the top and the side of the pastry dough with a THIN layer of egg wash. Bake for 20 mins or until the bases of the tarts are light golden. Please note that the baking time and temperature may vary a little if you use make your pineapple tarts in different shapes or sizes.

Allow the tarts to cool slightly on the baking trays for about 10 mins and transfer them onto a wire rack to cool completely.

Store in an airtight container at room temperature for up to 4 weeks depending on the type (with or without preservative, with full amount of sugar or sugar reduced) of pineapple jam that you used.