Onion Pie with Jarlsberg and Thyme

2 tbsp unsalted butter
4/5 red onions, cut into 0.5in slices
4 Garlic cloves, sliced
1 Bay leaf
5 Black peppercorns
2/3 whole cloves
Sea Salt
1 Sheet puff pastry
110g grated jarlsberg, gouda, parmesan or gruyere cheese

1) Heat the butter in a large skillet over a medium-high heat. Add the onions, garlic, bay leaf, peppercorns and cloves and lower heat to medium-low.
2) Cook for 20 mins, or until the onions are soft but not brown. Season with salt.
3) Preheat the oven to 200c/400f/Gas 6. Line a medium sized, oven-proof dish with the puff pastry.
4) Remove and discard the cloves, peppercorns and bay leaf.
5) Place the onions in the dish and add the grated cheese and 1 tsp of the thyme.
6) Bake on the lowest rack for 15 mins or until golden brown.
7) Sprinkle on the rest of the thyme and serve.