Steps
1. In a small bowl, beat the eggs and mix in the shredded cheese.
2. Heat a frying pan over medium heat and melt the butter.
3. Add the diced onions and sliced tomatoes to the pan and sauté until softened.
4. Pour the egg and cheese mixture into the pan and cook, stirring occasionally, until the eggs are fully cooked.
5. Toast the slices of bread until golden brown.
6. Spread the cheesy egg mixture onto one slice of bread and top with the sautéed onions and tomatoes.
7. Place the other slice of bread on top to form a sandwich.
8. Cut the sandwich in half and serve.