Wash the tomatoes, cut out the core ends, and slice crosswise into 1/2 inch slices.

Place the slices in a single layer on an oiled baking sheet.

Drizzle the melted butter or oil over the tomatoes and then sprinkle some salt and pepper.

Place the tomatoes in a boiler, 4 inches from the heat, and broil until half cooked.

Combine bread crumbs, butter, and onion. Sprinkle over the tomatoes.

Bring back the tomatoes inside the broiler and continue cooking just until the topping turns golden brown in color.