Heat the oil in a wide, heavy pot over medium-high heat and brown the chicken on all sides. Transfer to a plate. Add the butter, onions and thyme to the pan and cook until soft. Add the flour and stir to coat the onions. Add the stock, return the chicken to the pot and bring to a simmer. Cover and cook for 20 minutes. Stir in the carrot, peas and cream.
Meanwhile, stir together the flour, baking powder and salt. Stir in the cream. Drop the dough by the spoonful onto the simmering stew, spacing them an inch or so apart. Cover and cook until the dumplings have doubled in size, about 15 minutes.