Bring a large pot of salted water to a vigorous boil. Add elbow macaroni and cook until just shy of al dente, about 7 minutes. Drain and set aside.

In a medium saucepan over medium heat, melt 4 tablespoons of unsalted butter. Whisk in ¼ cup of all-purpose flour for about 1 minute until light golden.

Incorporate 3 cups of whole milk into the roux, whisking until smooth. Bring to a simmer and thicken for 3–5 minutes. Stir in cheese until melted.

Fold the cooked macaroni into the cheese sauce until fully coated.

Pour into a greased baking dish. Combine panko breadcrumbs, melted butter, salt, and black pepper. Sprinkle over the top.

Bake at 350°F for 20–25 minutes until golden brown and crispy.

Let rest for about 5 minutes before serving.