You’ll need a 20cm frying pan that can go into the oven. Roll out the pastry on a floured surface.
Sprinkle over fennel and cheese and fold dough in half. Roll out again to the same size as the pan and place in fridge to rest for at least 20 minutes. Melt oil and butter over low heat in a large ovenproof pan and sauté shallots until soft. Add sugar and thyme and cook slowly until caramelised.
Preheat oven to 200ºC. Remove from the heat but keep the shallots in the pan and spread them out evenly. Slice camembert and place on top of the shallots in the pan. Place puff pastry on top of the cheese.
Bake for 15 minutes then reduce the temperature to 180ºC and bake for 10 minutes until golden brown and cooked through. Cool slightly and turn over onto a serving plate.