Baked Chicken with stalks

1 chicken 1 onion , chopped 1 stalk celery , chopped 1/3 cup butter or 1/3 cup chicken fat 6 cups breadcrumbs 2 eggs 1/2 teaspoon baking powder 1 teaspoon[...]

4 tablespoons butter , divided 3 tablespoons olive oil , divided 1 lb boneless chicken breast , cut into cubes coarse salt and fresh black pepper 1 teaspoon[...]