Heat oven to 375 degrees. Cream butter and cream cheese with an electric mixer or food processor until light and fluffy. Slowly mix in the flour. On a lightly floured cutting board, knead the mixture a few times until it holds together. You want to touch this dough as little as possible or it will be tough. Chill dough for 15 minutes and then roll it out and cut into 2" rounds, around 1/4 inch thick. You can also cut into squares to make triangular pastries. Spoon 1/2 to 1 teaspoon jam onto each round or triangle and fold in half, carefully pinching the sides together to form a seal. Mix an egg yolk with a little water to make an egg wash and brush on the pastries. Bake for around 15 minutes or until tops are golden brown. (It is not unusual for the pastries to "leak" jam. Still tastes wonderful! Immediately remove the pastries to a cooling rack and dust with powdered sugar. Allow to cool a bit and serve warm.

This recipe can be made in advance and the pastries may be frozen and used as needed. Bake a little longer if you are baking the pastry from a frozen state!