In a bowl, whisk the eggs with chopped onion, parsley, salt, and paprika until well combined.
Heat a non-stick pan over medium heat and cook the egg mixture, stirring occasionally, until scrambled and set. Remove from heat.
Spread a thin layer of butter on one side of each slice of bread. On the unbuttered side, spread tomato sauce, then layer scrambled eggs, fresh tomato slices, and cheese.
Heat a pan or griddle over medium heat. Place the sandwich butter-side down and cook for 2-3 minutes, until golden brown and crispy. Flip and cook the other side until the cheese melts.
Remove from heat, slice in half, and serve warm.