Arrange half the bread slices in greased 8 x 12 inch baking dish. Mix crab meat, asparagus, onion and mayonnaise in a bowl. Spread over the bread slices. Mix the cheeses and sprinkle 1 1/2 cups over the crab meat mixture. Top with the remaining bread.
Mix eggs, milk, mustard, Worcestershire sauce, salt and pepper in a bowl. Pour evenly over the bread. Cover with plastic wrap and refrigerate for 2 hours or longer.
Remove plastic wrap and bake at 350 for 25 to 30 minutes or til puffed and light brown. Sprinkle remaining cheese over the top. Bake for 10 minutes longer or til cheese is melted and bubbly. Cool for 10 minutes before serving. Serves 8