Boil the eggs hard for about 10 minutes, quench and let them cool down. Peel onion and chop finely. Drain capers. Cut cucumber into fine cubes. Wash chives and cut into fine rings. Peel and finely dice the eggs. Mix onion, cucumber, capers, chives and egg cubes in a bowl, stir in crème fraîche, season with salt and pepper
Coarsely grate the cheese. Wash the salad, dab dry and arrange on the slices of bread. Cover the breads with 3 slices of ham, place the egg yolks and cheese on the ham and sprinkle with garden cress.