Cook the Pasta: Cook the macaroni according to package instructions in salted boiling water until al dente (7-8 minutes). Drain and set aside, tossing with a little olive oil to prevent sticking.
Make the Cheese Sauce: In a large pot, melt butter over medium heat. Add flour and whisk until bubbly, about 1-2 minutes. Gradually add milk and Half and Half, whisking constantly until smooth and thickened. Stir in pepper, nutmeg, garlic powder, and dried mustard. Add shredded cheeses and stir until melted and smooth.
Combine Pasta and Sauce: Stir the cooked macaroni into the cheese sauce until fully coated.
Prepare the Topping: Mix panko, melted butter, and seasoned salt in a small bowl until evenly coated.
Bake: Transfer the mac and cheese into a greased baking dish. Sprinkle the panko topping over the top. Bake at 375°F (190°C) for 20-25 minutes, until the top is golden brown and bubbly.
Serve: Let cool slightly before serving. Enjoy!