Mirlitons Farcis Aux Crevettes

Split the chayotes lengthwise in half.
Put in a kettle of cold water with salt to taste.
Bring to the boil and let simmer about 10 minutes.
Do not= overcook or the vegetable will become mushy.
Drain and run briefly under cold water.
Drain again.
Using a spoon, scoop out the flesh and seeds of each half, leaving a shell about 18 inch thick or slightly thicker.
Set= the shells aside.
Chop flesh and seeds fine.
There should be about 1 cup.
Peel and devein the shrimp and chop coarsely.
There should be about 1 1/4 cups.
Set aside.
When ready to cook, PREHEAT the oven to 425F (220C).
Melt half the butter in a saucepan and add the onion and garlic.
Cook, stirring, until wilted.
Sprinkle with flour and stir to distribute evenly.
Add the milk, stirring rapidly with a wire whisk.
When the sauce is thickened and smooth, add the= chopped pulp.
Bring to a boil, stirring, and add the ginger and scallions.
Remove from the heat and stir in the egg yolk.
Let stand to room temperature.
Stir in the shrimp, salt, pepper, 1/4 cup of the bread crumbs= and the parsley.
Use the mixture to stuff chayote halves.
Pile up and smooth over.
Blend the remaining 1/4 cup of bread crumbs and cheese.
Sprinkle the tops= with the mixture, patting to help it adhere.
Dot with the remaining 2 tablespoons butter.
Arrange the stuffed halves in a lightly buttered baking= dish and bake for 20 minutes.