Betty Crocker New Cookbook – This is also good by just sprinkling salt, pepper, and grated Parmesan over the tomatoes then baking. These extra ingredients below, though, really dress them up.
Heat oven to 350 degrees. Core the tomatoes, cut crosswise into ¾-inch slices. Place in single layer on rack in broiler pan. Mix mayonnaise, 1 tablespoon cheese, basil and mustard. Spread about 1 teaspoon over each tomato slice. Sprinkle 1 tablespoon cheese over tomatoes with tops 6 inches from heat 2 to 4 minutes until topping is golden and bubbly.