In a big freezer bag combine the flour, seasoning and onion powder. Pop the chicken pieces in and toss around until well coated. In a large casserole pot, heat one piece of butter and place half the chicken pieces in to brown well. Do the same with another piece of butter and second batch of chicken. Keep the remaining flour mix to one side. Brown off the mushrooms next with the remaining butter. Add stock and water, then return chicken to pan. Let simmer away until the chicken is cooked through, mixing occasionally. Mix up remaining flour with enough water to make a loose paste and whisk through the dish and continue cooking, stirring constantly until sauce has thickened. Enjoy!!!