Toast the English Muffins in a toaster then place on a lined baking sheet.
Prepare the tuna salad mixture: In a mixing bowl; combine the tuna, boiled egg, mayonnaise, celery, shallot and seasonings together until combined. Give a quick taste and adjust seasonings if needed.
Use a scoop or spoon to place equal portions of the tuna salad mixture on top of the toasted English muffins. Place a tomato slice on top of the salad mixture. Finally top with cheddar slices.
Bake 10 minutes or until cheese is melted.
Garnish with scallions, if desired, and serve hot.
Depending on appetite and how the tuna melts are served; a serving might be 1 melt (half an English muffin) if served with a side. You could also serve 2 melts, or both halves, of the English muffin as the meal.