Preheat oven to 375 degrees F. You’ll also need a 24-cup mini muffin tin.
On a lightly floured surface, roll pastry into a 12-by-12-inch square (slightly larger than the initial size of the sheet).
Cut into 25 squares.
Gently ease each square into a mini muffin cup.
Bake for 10 minutes or until puffed.
Press the center of each square down with the round end of a wooden spoon.
Bake for 3-5 minutes more or until corners are just starting to brown.
Place a piece of cheese into each cup.
Top with ¼ teaspoon of fruit preserves and a sprinkle of chopped pistachios.
Return to oven and bake until cheese is melted and bubbly and pastry is light golden brown, about 3-5 minutes.
Remove from oven and let cool for 5 minutes before removing from muffin tin.
Serve warm.
