In a small skillet, sauté leek in butter until tender. Add garlic and cook 1 minute longer. Stir in cream, salt, pepper and nutmeg. Cook and stir for 1 to 2 minutes or until thickened.
Preheat oven to 350°F (180°C).
Place tart shells on baking sheet. Slice cheese into 15 pieces. Place one piece in each shell and top each with 1 1/2 tsp (7 mL) of leek mixture.
Bake for 6 to 8 minutes or until heated through. Refrigerate leftovers.