Pat the chicken dry with paper towels, then season with salt and pepper. Heat s drizzle of oil in a large Dutch oven over medium-high heat uand brown the chicken until golden on both sides, working in batches so that you don't crowd the pan. Transfer the chicken to a plate, add a bit more oil (and a bit of butter if you like) and saute the onions until golden. Add the sherry and cook for a minute (it will almost cook off), scraping up any browned bits at the bottom of the pan (or you could use a bit of the stock or some water to do this), then add the flour and stir to coat the onions. Add the stock and thyme, then return the chicken to the pot and bring to a simmer; cover and cook over low heat for about an hour.

Meanwhile, stir together the dumpling ingredients. Take the lid off the pot (if you like, shred the chicken with forks and pull out the bones - you could refrigerate it at this point and do this with your fingers, then reheat when you want to), add the peas and cream and bring back to a simmer. Drop walnut to golf-ball sized dumplings over the top of the stew, about 1/4 inch apart. Cover and cook until the dumplings have doubled in size, about 15 minutes.

Serve warm.