Assemble all the tools and ingredients.

Preheat the oven to 350°F (180°C.)

Wash and trim the leeks, halve them lengthwise and slice.

Peel and core the apples and cut into chunks.

Heat the oil in a saucepan and add the leeks with a good pinch of salt. Sauté over medium heat until softened, but not colored, about 5 minutes.

Add the apples and thyme leaves, and carry on cooking for a further 2 minutes.

Add the beans and flour, and stir through. Cook until slightly nutty smelling, then pour in the cups vegetable stock.

Bring to a boil, then turn down the heat to a simmer. Cook just until you see the sauce thicken slightly.

Stir in the cheese and turn off the heat once melted. Season to taste, then split the filling between 4 small casserole dishes.

Roll out the pie dough on a surface with flour. Dust with flour and mark the circles. With a sharp knife, cut 4 circles a little larger than the top of your pie.

Lower the pastry circles on top of the vegetable filling and use a fork to press the sides onto the edges of the casserole dish to seal.

Bake in the preheated oven for about 20 minutes, until the flaky pie crust is golden brown, and the filling is bubbling up in a few places. Serve hot.