You will need a large casserole dish, lightly greased with a little olive oil or butter.

Preheat the oven to 350°F (160°C or 150°C for a fan oven).

Layer the vegetables with the sliced potatoes, and finally the chicken in the casserole dish.

Melt the butter in a medium saucepan over low heat. Whisk in the flour to make a roux. Cook for a minute or two, whisking constantly.

Whisk in the Madeira or sherry if using.

Gradually add the chicken stock, a little at a time, until the sauce becomes like a fairly thick soup. (You may not need all the chicken stock.)

Gradually add the milk, cream or half and half, a bit at a time, until the sauce is thick enough to help bind the vegetables and meat together, but not too thick (sort of like a cream soup). Once again, you may not need all the milk.

Carefully pour the hot sauce over the vegetables and meat in the casserole dish, stirring gently to mix through. Top with the stuffing, spreading it evenly over the top of the casserole.

Bake for 30 to 40 minutes, until the stuffing is turning golden brown and the filling is bubbling a bit. You can serve straight from the casserole at the table.