Preheat the oven to 240°C/Fan 220°C/Gas 9. Place a baking tray inside to warm up.
Toast the bread until very lightly browned on both sides. Set aside to cool slightly while you prepare the topping.
Put a small handful of the grated cheese (roughly 10g), 1 tsp chopped spring onion and a pinch ofgreen chilli to one side, to be used when you fry the egg(s).
Crack the egg(s) into a cup or small bowl, being careful to keep the yolk(s) intact.
Put the remaining cheese, spring onions and green chilli into a bowl, add plenty of black pepper and mix well. Using the back of a spoon (or your fingers), work the cheese mixture into a paste by pressing it firmly into the side of the bowl.
Spread the cheese mix evenly over the toast and press it in, using the back of the spoon, to create a firm, even layer that goes all the way to the edges of the toast. Place on the tray in the oven and cook for 6–8 minutes, until deep golden and bubbling.
While the chilli cheese toast is cooking, warm a frying pan over a high heat and, if using, add the oil. Gently tip the egg(s) into the hot pan and add some black pepper. Top with the reserved grated cheese, spring onion and green chilli.
Place the frying pan in the oven (important - check your frying pan is safe to use in the oven!) and cook for 2 minutes, or until the cheese is melted and the egg white(s) are cooked but the yolk(s) are still runny.
Carefully remove the frying pan from the oven (be careful, the handle will be hot!) and slide the egg(s) onto the cheese on toast and serve right away, with plenty of tomato ketchup, if you like that kind of thing!