Resep Gratin Ubi Jalar

Bahan-bahan (8 porsi)

• Olive oil spray
• 2 pounds ubi jalar
• 2 tablespoons minyak yg dicairkan
• 1 tablespoon fresh thyme leaves (chopped)
• 1 teaspoon garam halal
• Fresh black pepper
• 1 ounce finely grated Parmesan cheese
• 3/4 cup keju Gruyere parut