Slash the skin of the duck breasts in a criss-cross pattern down to the flesh. Cook the duck breasts over gentle heat 5 minutes skin side, 2 minutes flesh side (they should stay red). Cut them into thin slices.
Arrange the baby spinach leaves on a plate, cover them with the duck breast. Toast the buns on the barbecue, cook the slices of foie gras on the hotplate for about 1 minute on ea