Rabbit shepherd’s pie

Ingredients

• 1 rabbit (or 750g skinned and boned chicken thighs)
• 1 stalk celery
• 1 medium onion, peeled and finely chopped
• 2 small carrots, peeled and diced
• 1 small parsnip, peeled and diced
• 3 1/2 tablespoon olive oil
• 1 chorizo sausage, sliced
• 1 tablespoon chopped thyme
• 2 tablespoons chopped rosemary
• 1 tablespoon wholegrain mustard
• 2 teaspoons tomato concentrate
• 1/3 cup dry white wine
• 3 tablespoons plain flour
• 2 cups light stock or water
• 1 1/4 teaspoon salt
• 1.2 kilograms potatoes, such as agria (or a type good for mashing)
• 2 tablespoons butter
• 125 millilitres milk, heated
• 2 tablespoons finely grated parmesan cheese (optional)
• melted butter, for potato top