Coat chicken in flour. In a heavy based casserole dish put generous amount of butter and oil to lightly fry chicken on both sides until golden - then remove.
Brown whole baby onions and remove.
Sauté leek, pancetta, and button mushrooms for a few minutes then add cognac and white wine to deglaze pan.
Add chicken and onions back to pot then rest of ingredients.
Cover casserole dish and bake for about 1 hour in 180 deg oven
Serve with baby potatoes, turned carrots, peas and car keys!!!