Mix mayo and egg with salt, pepper and Old Bay. Reserve about 1/4-1/3 cup to glaze the top.
Fold into crab meat, tossing lightly.
Sprinkle the finely diced green pepper over the crab mixture
Pour the reserved mayo mix over the top and spread it using the back of a spoon to cover the crab.
Sprinkle with cracker crumbs followed by more Old Bay.
Bake at 350°F for about 30 minutes.