Chop the butter into small bits and add to a bowl.
Add the flour and caster sugar and with fingertips rub the butter into the flour until it resembles fine breadcrumbs.
Add the cold water and knead it in a little and roll into a ball.
Wrap the ball in clingwrap and put in the freezer for 20 minutes.
Preheat oven to 180 degrees celcius.
Remove from freezer and sprinkle some flour onto your worktop.
Roll out the pastry to about 3mm in thickness and cut shapes with a fluted cutter or scone cutter, cut them just a little larger than the hole in the tray.
Place into the tray and push down to make an indentation for the jam to go into.
Add 1 teaspoon of jam.
Place into oven and cook for 18-20 minutes.
Cool on a wire rack being careful as the jam is very hot.