Pumpkin and leek gratin

For 8-10 people
1 pumpkin Hokkaido
2 leeks (including green part)
1 piece of fresh ginger
1 sprig of rosemary
1 pinch of cayenne pepper
extra virgin olive oil
salt

For coverage
béchamel sauce
nutritional yeast flakes
breadcrumbs

Peel the leek and cut into slices the white part chopped and the green part.
Peel the pumpkin (also used the peel and remove only the seeds) and dice: the smaller and before they will cook.
Chop the ginger and rosemary needles.
Saute ginger in a large pan with a few tablespoons of oil, when it starts to sizzle add the leek and let it dry a little stirring constantly with a wooden spoons, then add the diced pumpkin, chopped rosemary needles, pepper, salt, a glass of water, stir and cover with a lid.
Cook over low heat, stirring occasionally and making sure that doesn't stick to the bottom, in which case add a little water.
After cooking the pumpkin with leek should be soft and discard turning them with a ladle, plus the water must have been completely absorbed.
While the filling is cooking, prepare the béchamel sauce.
When the vegetables are thoroughly cooked an oiled ovenproof dish and pour all the vegetables, then cover them with béchamel sauce.
Finish with a light dusting of nutritional yeast flakes and bread crumbs on top.
Bake at 200° C for 20-30 minutes, until the surface has taken on a gratin gilding.