Traditional Greek Moussaka

Name: Traditional Greek Moussaka
Ingredients: 1-1,5 kg big potatoes; 2-3 big eggplants; 1 cup kefalotyri cheese, grated; for ground meat; 500 gr ground beef; 1 onion, finely chopped; 1/2 clove of garlic, chopped; 1/3 cup olive oil; 2 ripe tomatoes, grated; 1/3 cup slightly concentrated tomato juice; 1 tablespoon finely chopped fresh parsley; 1/2 cinnamon stick; 2 allspice berries; pinch of nutmeg; salt and pepper to taste; for the bechamel sauce; 1 liter whole milk; 135 gr all purpose flour; 1 teaspoon salt; 1 egg; 1/2 cup kefalotyri cheese, grated; a pinch of nutmeg; pepper