In French this is called a Flamiche. It is a flan-like tart made with leeks cooked in milk to which lardons (pieces of trimmed slab bacon) have been added. As an impressive appetizer or a main course with a salad, this delicious Alsatian dish is always a hit—even with people who think they do not like leeks.
1 pie tart shell (Pillsbury, it can be used for savory tarts)
4 tablespoons butter, at room temperature
1 pound leeks
½ pound slab bacon
1⅔ cups boiled milk (I use skim)
2 tablespoons flour
Freshly ground pepper
Use 1 tablespoon of the butter to coat the pie shell. Roll out the dough and line a 9-inch pie plate with it. Poke with a fork five or six times and freeze until you are ready to fill it. (Freezing the pie shell helps it hold its shape and resist absorbing the liquid from the filling; poking the holes avoids air bubbles.)
Trim off and discard the green part of the leeks so that there is only the white. Cut the white into fine rounds. Wash in cold water, separating the rounds to ensure that all of the dirt between the layers is removed. Line a mixing bowl with paper towels, place the washed leeks in the bowl and pat dry with more paper towels. Trim and discard the fatty section of the bacon slab and trim the hard exterior of the meat side. Slice across the remains of the slab into small, thin bits (which are called "lardons").
Boil the milk and set aside. Preheat oven to 400° F. Melt 2 tablespoons of butter in a medium-large frying pan. Gently heat the lardons in the butter until they begin to color. Add the rest of the butter and the leeks on a very low flame and allow to cook slowly (not coloring) for about 15 minutes, stirring from time to time. Add half of the flour and stir. Add the rest of the flour and stir again. Allow to gently cook. Gradually add the milk (cold or warm), seasoning a couple of times with salt, pepper and nutmeg. Simmer on low heat for about 25 minutes. Remove pie shell from freezer, pour leek mixture into the shell and immediately place in the hot oven for about 20 minutes or until it turns golden brown. Remove from the oven and remove excess liquid with a paper towel. Serve piping hot in the pie plate or slide it onto a round plate.