Heat a drizzle of 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, celery, carrot and thyme to the pan and cook for a few minutes, until the vegetables are soft.
Add the flour and stir to coat. Return the chicken to the pot, add the stock and bring to a simmer.
Cover and cook for 10-15 minutes, until the chicken is cooked through and the sauce has thickened. Stir in the peas and cream.
Meanwhile, stir together the flour, baking powder and salt.
Stir in the cream.
Drop the dough by the large spoonful onto the simmering stew.
Cover and cook until the dumplings have doubled in size and are springy to the touch, about 15 minutes.