Baked Mushroom Wellington - the perfect holiday entree!

Ingredients

• 4 large portobello mushrooms, cleaned and stalks removed
• 4 ounces gourmet mushroom medley (baby portobello, shiitake, and oyster varieties)
• 3 large vidalia onions, sliced thinly
• 4 tablespoons olive oil, divided
• 2 tablespoons Worcestershire sauce
• 2 tablespoons of white wine
• 5 ounces of fresh baby spinach
• 1 teaspoon dried thyme, divided
• 2 teaspoons dijon mustard
• Sprinkle of garlic powder
• 1 frozen puff pastry dough sheet, thawed*
• 1 egg, beaten
• Salt and pepper to taste