Preheat the oven to 375°F (190°C). Boil salted water and cook macaroni until just al dente, about 1 minute less than the package says. Drain.

Melt butter in a saucepan over medium heat. Whisk in flour and cook for 1 minute until pale golden.

Slowly whisk in milk, then cook, whisking often, until thickened enough to coat a spoon, 3-4 minutes. Reduce heat to low and stir in cheddar, cream cheese, mustard powder, cayenne, and salt until smooth.

Fold the drained pasta into the sauce, then scrape into a 2-quart baking dish. Sprinkle panko evenly over the top and drizzle with olive oil.

Bake on the middle rack until bubbly and deeply golden on top, 20-25 minutes. Let rest 5 minutes before serving.