Baked sherry onions with nutty sourdough stuffing

Method

1. Preheat the oven to 170°C/fan 150°C/gas 3½. To hollow out the onions, slice off the tops and cut 1-2cm off the base, depending on the size. Push the middles of the onions from the base end so they slide out the top (or use a small knife to cut out the centres). Next, use your fingers to work out a few more onion layers, leaving 2-3 outer layers as a shell. Set the middles aside.
2. Put the onion shells in a roasting tin, then pour in 170ml of the sherry and all the stock. Cover the tin tightly with foil, then cook for 30 minutes, turning the onions halfway through.
3. Meanwhile make the stuffing. Whizz the reserved onion in a food processor until very finely chopped (but not a paste). Melt half the butter in a frying pan, then fry the chopped onion for 7-8 minutes until lightly golden. Season, then set aside. Melt the remaining butter in the pan, then add the breadcrumbs, chopped nuts and thyme. Season well and fry until golden. Return the fried onions to the pan with the garlic and the 100ml sherry, then bubble over a high heat until all the liquid evaporates. Take off the heat and allow to cool slightly, then stir through the egg yolks.
4. Remove the onions from the oven and pour away the liquid. Fill the shells with the stuffing, packing it firmly. Put the stuffed onions back in the roasting tin, dot with butter, then pour in the remaining sherry. Bake for 40 minutes, basting occasionally with the pan juices. The onions are ready when golden and crisp on top. Serve with a green salad.