Scalloped Potatoes and Butternut Squash With Leeks

Ingredients:

3 cups leeks washed very well and then thinly sliced about 6 large white and pale green parts only
1/2 cup unsalted butter
3 1/2 cups whole milk
6 tablespoons all-purpose flour
1 1/2 lbs potatoes about 4 large
1 lb butternut squash peeled seeded quartered and cut into 1/8 inch slices
1 1/2 cups gruyere cheese coarsley grated about 4 ounces

Preheat oven to 400 degrees
Generously butter a 3 quart baking dish at least 2 inches deep
In a skillet
cook leeks in 3 tablespoons butter over medium low heat
stirring
until very soft
In a saucepan
bring the milk just to boil dont scaldjust keep warm
In another heavy saucepan
melt the remaining 5 tablespoons of butter over medium low heat and whisk in flour - cooking and constantly whisking for about 3 minutes
Add heated milk in a stream
whisking
and bring to a boil
Simmer this sauce
whisking
for 1 minute - or until thickened - and season with salt and pepper
Peel potatoes and slice 1/8 inch thick
Spread about 1/3 sauce in baking dish and cover with 1/3 potato and squash slices
overlapping them slightly
Cover slices with 1/3 leeks and sprinkle with 1/3 Gruyere
Make 2 more layers with sauce
potatoes and squash
leeks and Gruyere in the same manner
Bake
covered with foil
in middle of the oven for about 20 minutes
Remove foil and bake 30 minutes more
or until top is golden and vegetables are tender Yum
If you prepare this in advance you may need to bake it a little bit longer