Preheat the broiler to medium-high heat. Lightly toast the bread in a toaster or pan-fry each side in a dry frying pan for a minute until golden.

Spread each slice of toast with a thin, even layer of mustard. Mix three-quarters of the sliced chiles into the grated cheese and layer it thickly over the toast.

Place the toast under the broiler until the cheese starts to blister and brown, then transfer to individual plates.

Melt the butter in a frying pan over medium heat. Fry the eggs until the whites have set and the edges are slightly crisp, but the yolks remain runny.

Place the eggs on top of the cheese toast. Sprinkle with salt, black pepper, and the remaining chiles. Serve immediately while the cheese is still bubbling.