Baked Mushroom Spinach and Chicken Gnocchi

Ingredients

• 1 tablespoon olive oil
• 1 (8 ounce) package sliced fresh mushrooms
• salt and ground black pepper to taste
• 2 tablespoons unsalted butter
• 2 tablespoons all-purpose flour
• 1 ½ cups whole milk
• 1 cup chicken broth
• ½ teaspoon salt
• ¼ teaspoon ground nutmeg
• ½ (3 pound) rotisserie chicken boned and shredded
• 1 (16 ounce) package potato gnocchi
• 2 cups baby spinach
• ¼ cup grated Parmesan cheese