Boil the spinach for about 5 minutes. Drain it by pressing it firmly with the back of a spoon. Dice the spinach and mix with the crumbled ricotta, half of the Emmental cheese and the beaten egg. Season with nutmeg, salt and pepper. Divide the dough into 8 portions and shape them.
Preheat the oven to 180°C. Arrange the burgers on a plate lined with greaseproof paper and sprinkle with the remaining Emmental cheese. Bake them at 180ºC for about 10 minutes. Grill them for 5 more minutes until the surface is lightly browned.
Serve them on toasted rolls with some lettuce leaves, tomato slices, gherkins cut into slices, and a few teaspoons of mustard and ketchup.
