I used a sweet vidalia onion instead of half the leeks. Really, any combination of onions, leeks, shallots and/or scallions would work fine. Variety is nice, and the red and green onions add visual appeal. Other cheeses would work too, of course...
9" pie crust
1 Tbls butter
3 medium leeks
2 bunches green onions
½ red onion
1 Tbls flour
1 C half-and-half
½ tsp salt
2 C shredded white cheddar
Preheat oven to 425°
Bake pie crust 15 minutes, or until lightly golden.
Meanwhile...thinly slice leeks (white and light green parts), thickly slice green onions including half the green stalks, slice the red onion - cut into thin half moon slices. Melt the butter in a large frying pan over medium heat; sauté 20 minutes or until very tender.
Whisk together flour, eggs, half-and-half, and salt. Add the cheese. Stir in ¾ of the onion mixture, and pour it all into the pie crust. Top with the rest of the sautéed onions. Bake 20 to 30 minutes (until a knife inserted in the center comes out clean. (If the edges start to get too dark, cover them with foil.)
Let sit 10 minutes before serving.