Cut "windows" from the bread leaving approximately 1.5 cm of borders. Place on a skillet spread with butter and gently fry for half a minute.
Into the "windows" put toppings: for example chopped ham or vegetarian toppings like corn or/and carrot with peas.
Sprinkle with chopped red onion.
Crack eggs into a deep bowl, beat with a fork and then pour into the "windows".
Cover with a trimmed (fitted to the "window") slice of cheese and the cut-out center of the toast and fry for approximately 1 minute until the eggs set slightly.
Flip with a spatula to the other side and fry for approximately 1/2 - 1 minute.
Sprinkle with chopped chives and cut in half, arrange on a plate and drizzle with ketchup.