In bowl, gently combine crabmeat, mayonnaise, celery, shallot, and Old Bay seasoning.
Place English Muffin halves on baking sheet and broil a few minutes in oven until lightly toasted.
Remove from oven and top with crab mixture, tomato and cheeses. Broil until cheese is melted.
Garnish with a sprinkle of Old Bay seasoning (or paprika) and parsley.
I layered the melts with the crabmeat mixture and Monterey Jack cheese then put under broiler for a bit to get the cheese to start to melt, then topped with tomato and cheddar cheese and broiled until melted.