Mushroom and Sweet Onion Stuffed Brie

Bahan-bahan (12 porsi)

• 2 tablespoons unsalted butter
• 1 tablespoon olive oil
• 1 teaspoon minced garlic
• ½ medium sweet onion, (thinly sliced)
• 8 ounces white mushrooms, (thinly slices (stems ok))
• ¼ cup sherry
• salt and pepper, (to taste)
• 1 wheel brie ((5 to 6-inches in diameter))
• 1 sheet puff pastry, (thawed)