Preheat oven (electric cooker: 200 °C/circulating air: 175 °C/gas: see manufacturer). Cut ham and cheese in half. Melt butter. Place 1 piece of ham and 1 piece of cheese on each end of a pastry sheet. Fold the rest of the dough sheet over in layers until it is used up, always brushing the dough with butter.
Put the croquettes on a baking tray lined with baking paper. Bake in the oven for 6-8 minutes.
Fry 4 fried eggs in 1 tablespoon of hot oil and season. Put them on the croquettes. Sprinkle with chives.