## Instructions
1. **Preheat Oven & Cook Pasta:** Preheat your oven to 375°F (190°C). Cook the elbow macaroni according to package directions until al dente. Drain well and set aside.
2. **Make the Roux:** In a large, heavy-bottomed pot or Dutch oven, melt the 1/2 cup of butter over medium heat. Once melted, add the flour and whisk constantly for 2-3 minutes, creating a smooth roux. It should be light golden in color.
3. **Whisk in Milk & Seasonings:** Gradually whisk in the warmed milk, a little at a time, ensuring no lumps form. Continue whisking until the sauce thickens and comes to a gentle simmer. Stir in the salt, black pepper, garlic powder (if using), and ground mustard (if using).
4. **Add the Cheese:** Remove the pot from the heat. Add 3 cups of the shredded sharp cheddar cheese and all of the Gruyere or Monterey Jack cheese. Stir until the cheese is completely melted and the sauce is smooth and creamy.
5. **Combine with Pasta:** Add the cooked and drained macaroni to the cheese sauce. Stir gently until the pasta is evenly coated.
6. **Assemble & Bake:** Pour the macaroni and cheese mixture into a 9×13 inch baking dish. Sprinkle the remaining 1 cup of sharp cheddar cheese over the top. If using, combine the panko breadcrumbs with the 2 tablespoons of melted butter and sprinkle evenly over the cheese.
7. **Bake:** Bake for 20-25 minutes, or until bubbling around the edges and the topping is golden brown. If the top starts to brown too quickly, you can loosely tent it with foil.
8. **Rest & Serve:** Remove from the oven and let it rest for 5-10 minutes before serving. This allows the sauce to set slightly and prevents it from being too runny.
**Short Tips**
* **Warm your milk:** This helps prevent lumps when adding it to the roux and ensures a smoother sauce.
* **Shred your own cheese:** Pre-shredded cheese often contains anti-caking agents that can make your cheese sauce less creamy.
* **Don’t overcook the pasta:** Remember, it will continue to cook in the oven, so al dente is key.
* **Experiment with cheese:** For a richer flavor, try adding a touch of smoked gouda or a sharper vintage cheddar.
* **For extra crispiness:** Broil for the last few minutes, keeping a close eye on it to prevent burning.
* **Make ahead:** You can assemble the mac and cheese, cover it, and refrigerate it for up to 2 days before baking. You may need to add a little extra baking time if baking from cold.
* **Storage:** Leftovers can be stored in an airtight container in the refrigerator for up to 3-4 days. Reheat gently in the microwave or oven.
