To make the filling, heat the olive oil in a large frying pan, and add the butternut squash. Add a splash of water, cover and cook for 10-12 minutes, stirring occasionally so it doesn’t stick. Add the eschalion shallots and cook for for 2-3 minutes until soft, before adding all the mushrooms. Cook for another 5-6 minutes before adding the crushed garlic and thyme for another minute. Season well.
Stir in the flour, cook for 1 minute and then pour in the white wine. Turn the heat up and bubble for 2 minutes before adding the stock and pre-cooked chestnuts. Bring to a boil, then simmer for 5-6 minutes until reduced and thickened slightly. Stir in the cannellini beans.
Meanwhile, preheat the oven to 180°C/fan 160°C/gas mark 4. To make the topping, stir together the melted butter, crushed garlic and parsley for the topping. Cut four 2cm thick slices from the round farmhouse loaf of bread. Trim them to sit snugly inside the pie dishes.
Go back to the filling and stir the crème fraîche and parsley into the mushrooms. Spoon the filling into four 400ml oval pie dishes, or ramekins, and then lay a piece of bread on top of each. Brush with the garlic butter and cook in the oven for 20 minutes, until the tops are golden brown. Serve immediately.