Using a 2 1/2-inch round cookie cutter, cut a hole from the center of each bread slice. In an extra-large nonstick skillet heat oil over medium-high heat. Add bread slices; cook about 1 minute or until lightly toasted. Turn bread over.
Break an egg into a cup, taking care not to break the yolk. Hold the lip of the cup as close to the hole in one of the bread slices as possible and slip egg into hole. Repeat with the remaining eggs. Reduce heat to medium. Cook, covered, for 5 to 6 minutes or until whites are completely set and yolks begin to thicken.
Transfer egg toasts to serving plates. Top with tomatoes and, if desired, green onions. Sprinkle with cheese.