Philly Cheesesteak Cheesy Bread (Hot and Melty)

Ingredients

• 1 large French bread loaf, about 16 oz (450 g), split lengthwise
• 3 tablespoons (42 g) unsalted butter, melted
• 2 cloves garlic, finely minced
• 1 tablespoon chopped fresh parsley, plus more for garnish
• 1 tablespoon vegetable oil
• 1 medium yellow onion, thinly sliced
• 1 green bell pepper, thinly sliced
• 1 cup (75 g) sliced mushrooms
• 1 1/4 lb (565 g) shaved ribeye or sirloin steak
• 1 tablespoon Worcestershire sauce
• 1 teaspoon Italian seasoning
• 3/4 teaspoon kosher salt, plus more to taste
• 1/2 teaspoon black pepper
• 10 slices provolone cheese
• 1 cup (115 g) shredded mozzarella cheese