1 sheet filo pastry square sheet
300 g Greek natural yogurt
150 g spinach - roughly chop - rinse before use
1 tablespoon olive oil
1 onion - peel, cut in half and thinly slice
2 cloves garlic - peel and finely grate
250 g white mushrooms - clean with a dry brush, cut off the stem then roughly cut into slices
4 sprigs thyme - leaves only, remove the stalks
150 g gruyère cheese - finely grate
salt - to your taste
black pepper - freshly ground from a pepper mill, to your taste
230 °C
