This is all out comfort food and is delicious served with or without the bacon.
Pre heat the oven to 200c. Place the pumpkin wedges in a greased roasting tray. Drizzle them with oil and scatter them with a little salt. Roast them until they are tender but still holding their shape. Allow them to cool until you can handle them directly, then peel the skins away with a pairing knife or even your fingers. It is very easy and now you can cook the pumpkins again briefly without getting a runny gratin.
Cut the pumpkin into whatever sized chunks you want and fill a baking dish with them. Heat the butter and oil in a good sized pan and fry the bacon until it is quite crispy. Add the garlic and onions and fry until tender.
Throw in the sage leaves and wilt them into the mix. Set all this aside. Add the flour to the pan with a little more oil if it needs it. Let the flour gather up some of the debris from the frying onions and bacon. Now add enough of the milk to make a paste, then add the rest and cook until you have a smooth sauce. Add the cheese and mustard, then remove from the heat, stir in the onions and bacon mix, whisk in the egg yolks and check the seasoning. Pour the sauce all over the pumpkin and bake until the top has gone golden brown.
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