Clean, wash and slice the leek. Dice the cooked ham.
Sauté the leek in olive oil, sauté the ham briefly and season everything with salt and pepper. Cook the gnocchi, drain and mix with the leek and ham mixture. Put everything in a baking dish. Peel the garlic, chop finely or press (depending on your taste), mix with the crème fraîche and season with the Italian herbs, salt, pepper and a little lemon juice. Spread the crème fraîche sauce over the gnocchi, sprinkle with the cheese and bake the casserole in the oven at 200 degrees on the middle rack for about 25 minutes until golden.