4 tablespoons butter or margarine
4 tablespoons all-purpose flour
2 cups half-and-half or heavy cream
1/2 cup (or more to taste) grated Parmesan cheese
Salt and white pepper to taste
Few grains cayenne pepper (optional)
6 to 8 ounces cooked snow crab meat, cut into chunks

Melt the butter in a saucepan. Stir in the flour, and cook briefly until the mixture looks sandy. Do NOT let it color. Wisk in the half-and-half or heavy cream, and stir until the mixture forms a thick sauce. Stir in the cheese, and season to taste. Simmer for a few minutes to blend the flavors, and stir in the crab meat. Cook only until the crab is heated through.

Serve over cooked linguini, with additional Parmesan cheese and hot red pepper flakes on the side.