Stuffed Zucchini with Ham and Mushrooms

Ingredients (10)

• 4 medium sized zucchini (at least 1/2 pound each) OR 3 large zucchini (3/4 pound each) OR 1 jumbo zucchini (2 pounds)
• 4 Tbsp butter, divided
• 1 medium onion, chopped (about 1 cup)
• 10 ounces of fresh mushrooms, sliced
• 1/2 cup finely chopped ham
• 2 teaspoons finely chopped parsley
• 1/2 teaspoon Worcestershire sauce
• Salt, pepper, and cayenne to taste
• 1/3 cup breadcrumbs
• 1/3 cup grated Gruyere or Parmesan cheese