Personally, if I could get the right potatoes and the ducks were laying I'd have duck eggs and chips with lashings of bread and butter. But, yeah, that's not really festive nor is it even remotely traditional.
For many years we had cheese and lentil loaf, then when Quorn invented their chicken styled roast we had that. It was barely adequate and I hate it (although it does work quite well in sandwiches with mustard pickle). A few years ago... Bloody hell, getting on for 10 now, doesn't time fly? I came up with an idea for some kind of festive parcel using puff pastry (bought because I couldn't be arsed to make it) and roasted vegetables, nice cheese and an assortment of interesting other things. Over the years it has changed slightly, depending on what's available or what I fancy, but it is essentially the same basis.
This year the turkey alternative is going to be the following:
1 pkt puff pastry (ready rolled, enough for two large parcels)
an assortment of roasted vegetables; this year they will be: shallots or a red onion, butternut squash, red and green peppers, some garlic and a little bit of swede (the yellow ones, not turnips). Don't over cook them. Once the peppers are taking a brownish edge to them, whip them out. You want to roast these with a little olive oil, some salt and black pepper and a wee sprinkle of fresh lemon juice.
In a frying pan, make a sort of duxelle. Mushrooms, red onion, herbs, a drop of wine and in this case some chopped up chestnuts. Now fresh chestnuts are a bugger to peel so you can do one of two things - you can boil them for about ten minutes and the skins will peel off quite easily, or you can just persevere with them, scraping, gouging and generally trying to get the membrane away from the flesh. If you have dried ones, like wot I have and did myself, you can reconstitute them in warm water until you can cut or break them up.
Put your roast veg in a bowl, put your super duxelle in with it and then add about a cup of brown rice - cooked and this year I will be putting a tablespoon or two of sage and onion stuffing mix (actually it's chive, leek and thyme, but whatever festive stuffing mix you have a tablespoon really puts the festive into these parcels). Mix it all together and then grate some Gruyère into it. I'd just put enough in to a) mix it together as a nice sort of meat loaf texture and b) so that it isn't over powered by the cheese flavour. Season this and get some sage leaves (we have a bush in the garden) and cut half a dozen leaves into thin strips and add that to the mix.
Prepare your pastry, spoon your mixture in and fold your pastry over to make your pasty shaped parcel; egg wash them. Pop them in the oven and when they've risen and are nice a golden brown, take them out and serve with roasted Mayan Gold potatoes, Brussel sprouts, roasted parsnips (always par boil them for a few minutes before putting them in the oven) carrots, peas and BISTO gravy. Original Bisto doesn't have any meat extracts in it; spice it up a touch by adding a little reduced red wine and a little bit of a good bouillon and some of the fat from your roasted spuds.