Whisk together mayonnaise, egg, mustard, Old Bay, lemon juice, salt, pepper, and Tabasco, then gently stir in crabmeat. Chill, covered, 2 hours.
Pulse cornflakes in a food processor until coarsely ground and put in a shallow dish. Form 1 heaping teaspoon crab mixture into a 1 1/2-inch-diameter cake (mixture will be very moist), then gently dredge in cornflakes. Make more crab cakes in same manner, transferring to buttered baking sheets. Chill, covered, at least 1 hour.
Preheat oven to 400°F.
Bake crab cakes in batches in middle of oven until crisp and golden, 8 to 10 minutes. Transfer with a spatula to a platter and top each with about 1/2 tablespoon tomato ginger jam.
