It's called a grilled cheese, so why not make it on the grill? Multiply this recipe by the number of people you're serving, then set out all the toppings and let everyone make their own creations.
Preheat grill to medium-high.
Brush one side of each slice of bread with butter (or mayonnaise). Brush or sprinkle the other side of one slice with flavoring. Top with 1 slice cheese, vegetables, then the remaining slice of cheese. Top with the remaining slice of bread, butter (or mayo) side up. Place the sandwich on a piece of foil.
Grill the sandwich on the foil, flipping once, until the cheese is melted and the bread is toasted, about 1 minute per side.
Nutrition values shown are with butter, basil, sharp Cheddar and tomato.
Nutrition bonus: Vitamin A (38% daily value), Vitamin C (29% dv).