1. Preheat and Prep: Preheat your oven to 350°F (175°C). Grease a 9×13-inch baking dish with butter or cooking spray. Shred your cheeses and set aside.
2. Cook the Pasta: Bring a large pot of salted water to a rolling boil. Add the elbow macaroni and cook for 2 minutes LESS than package directions (it should be quite firm). Drain well and set aside. Don’t rinse the pasta—the starch helps the sauce cling better.
3. Make the Roux: In a large saucepan over medium heat, melt the 4 tablespoons of butter. Once melted and bubbling, add the flour and whisk constantly for 2-3 minutes until the mixture turns light golden and smells nutty. This cooks out the raw flour taste.
4. Add the Milk: Gradually pour in the milk while whisking constantly to prevent lumps. Add the heavy cream and continue whisking. Bring the mixture to a gentle simmer, stirring frequently. Cook for 3-4 minutes until the sauce thickens enough to coat the back of a spoon.
5. Add Seasonings: Stir in the dry mustard, garlic powder, onion powder, salt, black pepper, and cayenne (if using). Whisk until everything is well combined.
6. Melt the Cheese: Reduce heat to low. Add the shredded cheddar and Gruyere one handful at a time, stirring after each addition until completely melted and smooth. Don’t rush this step—adding cheese gradually prevents clumping. The sauce should be silky and coat the spoon heavily.
7. Combine Pasta and Sauce: Remove the cheese sauce from heat. Add the drained pasta to the sauce and stir gently until every piece is coated. Taste and adjust seasoning if needed—this is your last chance before baking!
8. Transfer to Baking Dish: Pour the mac and cheese mixture into your prepared baking dish, spreading it evenly. Use a spatula to smooth the top.
9. Make the Topping: In a small bowl, combine the panko breadcrumbs with melted butter and paprika. Mix until all the crumbs are coated with butter. Sprinkle evenly over the mac and cheese.
10. Bake: Place the baking dish on the center rack and bake uncovered for 25-30 minutes, until the top is golden brown and the edges are bubbling. If the top browns too quickly, tent loosely with foil for the last 10 minutes.
11. Rest and Serve: Remove from the oven and let rest for 5-10 minutes before serving. This allows the sauce to thicken slightly and makes serving easier. Dig in while it’s hot and bubbly!

Notes

• Cheese Temperature: Bring cheese to room temperature before adding to the sauce for smoother melting.
• Don’t Overcook Pasta: Undercook the pasta by 2 minutes since it continues cooking in the oven.
• Fresh is Best: Always shred block cheese yourself—pre-shredded cheese doesn’t melt as smoothly.
• Leftovers: Store covered in the refrigerator for up to 4 days. Reheat portions in the microwave or oven.
• Scaling: This recipe easily doubles for a crowd. Use a larger roasting pan or two 9×13 dishes.