4 dozen mussels, in shells
4 ounce butter
2 tablespoon flour
1 small onion, minced
1/2 cup cheddar cheese, crumbled
salt and pepper
1 cup mussel broth
2 tablespoon sherry
1 cup cracker crumbs
watercress
Select large, fresh mussels with shells closed. Scrub shells well and rinse under running water. (If time allows let mussels soak 2 hours in large pot filled with water. Discard any mussels that float.) Pour 1 inch of water into large kettle; add 1 teaspoon salt and mussels. Cover and steam 3 minutes or until shells begin to open. Remove and drain. Strain broth thorugh fine sieve; set broth aside. Take mussels from shells; remove dark, hairy beard; set meats aside. Melt 2 ounce butter in saucepan over medium heat. Add onion and sauté gently for 5 minutes, or until golden brown. Gradually add flour, stirring continually. When very smooth, slowly add 1 cup mussel broth. Continue stirring until sauce is thick (about 5 minutes). Add salt, pepper, and sherry. Make sauce of desired thickness by adding more mussel broth if necessary. In casserole arrange alternate layers of musselos, sauce, cracker crumbs, and light sprinkling of cheese until ingredients are all used. Save sufficient crumbs and cheese for top layer. Dot top with other 2 ounce of butter. Bake in preheated 350 degree F. oven for 15 minutes or until top is golden brown.