Place the chopped butter in the freezer for 10 minutes to firm up then place it in the food processor with the flour and salt.

Blitz it together until the mixture looks like wet sand then add the iced water and process until it forms a dough.

Turn the dough out onto a piece of plastic wrap and shape into a disc then wrap it up.

Refrigerate the dough for at least an hour.

Grease a tart tin with butter then line the base with baking paper.

Roll the pastry out to about 3mm thickness and then carefully lift it over the tart tin.

Use your fingers to gently lift and push the pastry into the tin to fit then give it a trim so that the pastry extends about 2cm over the side of the tin.

You may need to pleat it so it stands up.

Cover the pastry and pop it in the freezer for 15 minutes to firm up.

Pre-heat the oven to 180C.

Place a sheet of baking paper in the middle then fill it with pie weights (I use dried kidney beans that I keep in the fridge and re-use).

Bake for 30 minutes or until it is golden then transfer to a wire rack to cool.

Meanwhile make the onion mixture.

Heat the olive oil in a large frying pan then sauté the onions, stirring every now and then and scraping the bottom, until they are soft, transparent and start to get a little golden.

Add the garlic and the thyme and cook for a few more minutes.

Turn off the heat and stir through the parmesan then season with salt and pepper.

Spread the onion mixture out onto the cooled pastry base and then top with the tomatoes and crumbled feta.

Bake for 20 minutes or until the tomatoes are soft and mushy and the feta golden.

Garnish with a few extra sprigs of herbs from the garden and serve warm.