Hamburger Helpa - Valerie Bertinelli

Ingredients

• 2 tablespoons unsalted butter
• 1 pound ground 90% lean beef
• 1/4 teaspoon black pepper
• 1 teaspoon kosher salt
• 8 ounces uncooked elbow macaroni
• 2 cups whole milk
• 1 1/4 cups warm water
• 1/4 teaspoon dry mustard
• 1/4 teaspoon paprika
• 1/4 teaspoon garlic powder
• 1/8 teaspoon cayenne pepper
• 1 1/2 cups shredded sharp Cheddar cheese
• 1/2 cup chopped American cheese
• 2 tablespoons thinly sliced fresh chives
• 1/4 cup panko (Japanese-style breadcrumbs)
• 1 scallion, green part sliced