Add the mushrooms and cook over a medium heat until softened. Add the spinach and wilt.
Mix in the stilton.
Meanwhile place the puff pastry on a chopping board and cut it in half along the short axis. For each half, score it in the middle along the short axis.
Place a large spoonful of the mushroom mixture on one side of the scored pastries.
Fold over the other half of the pasty and seal with a fork.
Cut a slit in the top to allow steam to escape.
Place the pies on a baking tray in the oven for 20 minutes or until golden brown.
Notes
Take the pastry out of the fridge ten minutes before use.