1. Roll your pastry out onto a floured surface into a rough rectangle of about 30cm by 20cm but you don’t need to be too precise about it. Place on a lined baking tray and then into the fridge to chill.
2. Preheat your over to 200C/Gas 6.
3. Heat a large frying pan over a medium eat then add the button and fry your mushrooms in it for 5 minutes with the garlic and half of the parsley.
4. Remove from the heat then mix with the two cheeses and season with a pinch of salt and plenty of black pepper. Don’t be shy with the pepper here.
5. Remove your pastry from the fridge and score a border around it about 1cm from the edge. Place your mushroom mixture into the centre ensure none of the mixture goes on your border.
6. Brush the edge with your beaten egg and place in the over for around 20 minutes or until it is fully puffed up and golden.
7. Serve it up as soon as it leaves the oven and for a real summery dinner serve with a crisp fresh salad.