Velvety Steakhouse Creamed Spinach

Ingredients

• 4 tablespoons unsalted butter
• 1/4 cup all-purpose flour
• 1/2 cup grated mozzarella cheese
• 1 teaspoon freshly ground black pepper
• 1/4 cup cream cheese
• 1 medium yellow onion, minced
• 1 teaspoon Kosher salt
• 3 1/2 cups half-and-half
• 2 1/4 pounds fresh leaf spinach, roughly chopped
• 1/2 cup grated Parmesan cheese
• 3 cloves garlic, minced
• 1/2 teaspoon freshly grated nutmeg