Mac and Cheese - Once Upon a Chef

Ingredients

• 1 pound (16 ounces) macaroni, cavatappi or penne pasta
• 1 stick (½ cup) unsalted butter, divided, plus more for greasing the pan
• ½ cup all-purpose flour
• 5 cups whole milk
• 12 ounces Gruyere, shredded (about 4 cups)
• 8 ounces extra-sharp Cheddar, shredded (about 2 cups)
• ⅔ cup grated Parmigiano-Reggiano
• 1 teaspoon salt, plus more for the pasta water
• ½ teaspoon ground black pepper
• ¼ teaspoon ground nutmeg
• 1 cup panko bread crumbs
• 1 teaspoon herbes de Provence or dried thyme