1.Preheat oven to 200Â°C/400Â°F/Gas Mark 6, 15 minutes before baking. Heat oil in a pan and gently sautÃ© onion and pepper for 5 minutes. Add mushrooms and continue to sautÃ© for 3 minutes or until the mushrooms have wilted. Remove from heat and stir in parsley with seasoning to taste. Cool then drain.
2.Place pastry sheets, lattice side down on work surface and divide the drained mushroom mixture between the sheets, placing it down the centre.
3.Wipe breast fillet steaks and place on top of mushroom mixture. Brush edges lightly with beaten egg and wrap pastry round completely encasing the fillet. Pinch edges firmly together to seal.
4.Turn parcel over and place on a lightly oiled baking sheet. Brush with a little beaten egg.
5.Bake in preheated oven for 25-30 minutes or until pastry is well risen and golden brown. Serve with seasonal vegetables or salad.