- Preheat the oven to 375˚F (190˚C).
- Heat the oil in a frying pan on high heat. Sauté the onions and mushrooms for 5 minutes, stirring often. Stir in the chicken stock and cream, and bring to a boil.
- Lower the heat to medium-high. Reduce, uncovered, for 8 minutes, stirring often. Add the chopped bacon, and season with salt and pepper, to taste. Stir and set aside.
- Sprinkle flour on a work surface and roll out the puff pastry dough to a thickness of 5 mm (1/4 in.). Cut into 4 rectangles and spread the mushroom mixture on half of each rectangle.
- Brush beaten egg on the edges and fold over the puff pastry, pressing the edges together securely with your fingers or a fork.
- Brush beaten egg on top of the puff pastries. Place them on a cookie sheet and bake for 40 minutes or until crisp and golden brown.
- Serve as an appetizer on a bed of greens.
Variation: For delicious bite-sized hors d'oeuvres, cut the puff pastry dough into 12 rectangles and bake for about 25 minutes.