Vacherin pithivier with caramelised onions and bacon

Method

1. Remove the top of the box from the cheese, then snip away the box around the sides and peel off the thin wooden spruce coating from the skin of the cheese. Keep it on its wooden base and put in the freezer while you prepare the other bits.
2. Heat a large frying pan over a high heat and fry the pancetta until crisp. Remove using a slotted spoon and set aside. Add the onions and thyme to the pan, turn the heat to medium high and cook, stirring often, for 20-25 minutes until the onions are soft and well caramelised. Turn the heat back up, pour in the wine and bubble until almost completely evaporated. Put in a bowl to cool. Stir in the cooked pancetta.
3. Unroll a pastry sheet, keeping it on its paper, and cut out a rough 22cm diameter circle, then put it, still on its paper, on a baking sheet. Take the vacherin out of the freezer and invert it onto the middle of the pastry. Ease off the wooden base, then top the cheese with the onion mixture, patting it down and making sure none topples onto the pastry.
4. Brush beaten egg over the pastry in a 2-3cm border around the cheese. Roll out the other pastry sheet on a floured surface to 2-3cm wider so it’s big enough to cover the filling. Drape it over the cheese, pressing it down onto the egg-washed pastry edge to make a 3cm lip around the cheese. Squeeze out any air as you go. Once sealed, trim around the 3cm border with a knife to form a neat circle, then press a fork around the edge of the pastry to decorate the lip and completely seal the pithivier. Brush all over with beaten egg and chill for 30 minutes (or in the freezer for 10). Heat the oven to 200°C/180°C fan/gas
5. Brush the firmed-up pastry all over with beaten egg again, then score a pattern of curved lines on top using the tip of a sharp knife. Be careful not to cut through the pastry – just let the weight of the knife score the surface. Bake for 30-35 minutes until dark golden and glossy. Transfer to a lipped platter (to catch the runny cheese), leave to stand for 10 minutes, then slice to serve. Depending on its ripeness the cheese may be quite runny, so have a spoon ready to scoop it up. Serve with a crisp green salad.