Step #1 Split tomatoes in half with serrated knife.
Step #2 Mix together the mayo, parmesan & garlic powder/garlic salt (you can add more of anything to taste).
Step #3 Spread the mayo cheese mixture on top of each open tomato.
Step #4 Broil in toaster oven or oven broiler until the mayo is bubbly & the cheese is lightly brown/melted --
This is really good [from my daughter's wicked stepmother].