In a medium-sized bowl, mix together the flour and salt. Dice the butter into small pieces and crumble it with the flour until lumps are the size of small peas. Pour in the ice cold water, little at a time, mixing with a fork. Finish by hand and shape into a ball. Flatten the dough a little bit, wrap into cling film and chill in the refrigerator for about 1 hour.

Preheat the oven to 425°F (220°C). Grease the bottom and sides of a 9-inch (23 cm) pie dish with butter and dust with flour.

Melt butter in a large skillet placed over medium heat. Add the shallots, carrots, and leeks. Cook for about 10 minutes, stirring often, until golden and tender. Add the mushrooms, and cook for 3 more minutes, then add garlic and cook for one more minute. Deglaze with white wine* until evaporated, stirring often. Whisk in the flour, salt, pepper, nutmeg and fresh thyme. Slowly add the water/broth** and cream, stirring frequently until thick, about 10 minutes. Let cool at room temperature.

Roll out the pie crust into a large circle, about 12-inch (30 cm) in diameter. Carefully place over the pie dish, prick with a fork and pour the filling over, then pour the cooled filling on top.

In a small bowl, mix breadcrumbs with melted butter. Sprinkle breadcrumb mixture on top of the pie and bake for about 30 minutes or until the crumble topping is golden. Check the pie after 15 minutes, and place a piece of foil loosely over the top if the top starts to brown, then continue baking. Allow to cool slightly and serve!