1. Preheat your oven to 350°F (175°C). Grease a 9×13-inch baking dish and set aside.
2. Bring a large pot of salted water to a boil. Add the elbow macaroni and cook until just al dente, about 7 minutes. Drain and rinse briefly under cold water to stop cooking. Set aside.
3. In a large saucepan, melt the butter over medium heat. Once melted, whisk in the flour and cook for about 1-2 minutes, stirring constantly. This forms a roux, which will thicken your sauce.
4. Slowly pour in the warmed milk while whisking continuously to avoid lumps. Continue cooking, stirring often, until the sauce thickens and coats the back of a spoon, about 5-7 minutes.
5. Remove from heat and stir in the Dijon mustard, garlic powder, onion powder, salt, and black pepper. Then, gradually add the cheddar, mozzarella, Gruyère, and half of the Parmesan cheese. Stir until all the cheese melts into a smooth, creamy sauce.
6. Fold the cooked macaroni into the cheese sauce, ensuring every noodle is luxuriously coated.
7. Pour the cheesy macaroni mixture into your prepared baking dish and smooth the top.
8. In a small bowl, combine the panko breadcrumbs with olive oil or melted butter. Sprinkle this mixture evenly over the mac and cheese. Then, dust the remaining Parmesan cheese on top for an extra golden crust.
9. Bake in the preheated oven for 25-30 minutes, or until the top is golden brown and bubbly. If you want a crispier top, broil for an additional 2-3 minutes—just keep a close eye on it.
10. Remove from oven and let it rest for 5 minutes before serving. This step helps the bake set, making it easier to serve and enjoy.

When Mama Lou taught me to bake, she always emphasized patience, especially with dishes like this. Rushing to dig in right out of the oven means you’ll burn your tongue—but waiting just a bit brings out the full flavors and lets the cheese meld beautifully.