Toast slices of bread, brush with butter and place on a baking sheet.
Separate the eggs and set aside the yolks in the shells.
Beat egg whites until stiff.
Puree the drained anchovy fillets and fold into the egg whites. Spread this mixture over the toasts. Slide one egg yolk into the middle and sprinkle cheese over it.
Put the tray in the preheated oven on the middle rack and bake the toasts for 10-12 minutes.