Melt butter in top of a double boiler. Add green pepper and onion. Cook over boiling water until tender, about 10 minutes.
Blend in flour, mustard, milk, and shredded cheese. Cook, stirring constantly until cheese is melted and very thick.
Add in crabmeat, tomatoes, Worcestershire sauce, and salt. Blend thoroughly. Pour into two-quart casserole.
Sift together biscuit flour, baking powder, and salt. Add in shredded cheese and cut in shortening. Add milk, and mix only until flour is moistened.
Drop biscuits by rounded teaspoonfuls on top of the hot crabmeat mixture.
Bake in a hot oven (450 degrees) for 20 to 25 minutes.
Yield: 6 to 8 servings