This spinach and mushroom pie is vegetarian food at its best: buttery fried mushrooms and wilted spinach, bathing in a garlic, thyme and white wine gravy, topped with crispy and flaky puff pastry.
Warm the oil over a gently heat, then add the garlic and thyme with a pinch of salt and pepper and fry gently for 30 seconds until the oil sizzles.
Add the sliced onions and increase the heat to medium. Sweat for 5 minutes until starting to soften.
Add the butter and allow to melt, then add the sliced mushrooms, frying for another 5 minutes until dark and soft.
Add the stock and wine. Bring up a simmer and allow the wine to cook off for a minute.
In a bowl, mix the cornflour with a little of the liquor from the pan until smooth and then add to the pan. Continue to stir on the heat for 5 minutes until thickened.
Add the spinach and cook for just a minute or two, until the spinach has wilted.
Allow to cool to room temperature.
Assemble the pie
Spoon the cooled mushroom filling into your pie dish.
Put the pastry sheet on top of the pie dish, press a fork around edges, then cut away the excess. You can use the offcuts to add some decorative elements, if you like.
Brush the top with the beaten egg.
Cut two small slits in the centre of the pie to allow steam to escape.
Bake for 20-25 minutes until puffed up and a rich, golden brown.