Caramelised onion and goat cheese tart

Caramel tart image
This is a classic goat cheese recipe. It contrasts the sweet, caramelised onion with the sharpness of the goat cheese and is topped off with a rich, crumbly pastry.
you will need: 
caramelised onion filling 
1kg onions, finely sliced 
125g butter 
1 tub chilli billy goat cheese 
(or other billy goat cheese) 
short crust pastry 
2 cups plain or wholemeal flour 
½ tsp salt 
150g butter, cut into small cubes iced water 
To make short crust pastry, sift flour and salt into a bowl. Gently rub in butter with fingers to make small crumbs. Add small amounts of water while mixing. Finished pastry will come away from the bowl in a soft lump. Cover with cling film and place in fridge for 30 minutes. 
To make the filling, melt butter in a saucepan and add the chopped onion. Cook slowly until caramelised. This may take up to an hour. 
Roll out the pastry roughly matching the shape of the baking tray. Spread the onion mixture around the middle and place teaspoons of chilli billy over the mixture. Fold the edges of the pastry back over the top of the pie to form rough sides. 
Bake in oven at 180ºC until the pastry is golden, about 20 minutes. 
Cheesemaker’s tip: You can substitute the short crust pastry with prepared puff pastry if you’re short of time.