Preheat the oven to 400 degrees F (204 degrees C). Grease a 9x13-inch baking dish.

Bring a large pot of lightly salted water to a boil. Cook elbow macaroni in the boiling water, stirring occasionally, until tender yet firm to the bite, about 8 minutes. Rinse under cold water. Drain well.

Melt butter in the same pot on medium heat; sprinkle with flour, ground mustard, black pepper, garlic powder, and salt. Cook and stir until well blended, about 2 minutes. Gradually stir in milk; cook, stirring constantly, until sauce begins to thicken, about 3 minutes.

Stir in cheese until melted and smooth. Off heat, gently stir in macaroni until coated. Transfer to the prepared baking dish. Combine panko and paprika; evenly sprinkle over top.

Bake in the preheated oven until bubbly and golden brown on top, 25 to 30 minutes. Let stand 5 minutes before serving.