Step 1: Cook the Pasta

1. Bring a large pot of salted water to a boil.
2. Cook the macaroni until al dente, about 1-2 minutes less than package instructions.
3. Drain and rinse under cool water to stop the cooking.
4. Toss with 2 tablespoons of melted butter to prevent sticking.

Step 2: Make the Cheese Sauce

1. In a large saucepan over medium heat, melt the remaining 2 tablespoons of butter.
2. Stir in the heavy cream and whole milk, warming it up without boiling.
3. Whisk in the seasonings—salt, black pepper, garlic powder, onion powder, smoked paprika, and mustard powder.
4. Reduce heat to low and gradually stir in the shredded cheeses, ensuring they melt smoothly.
5. If using Velveeta, add it now and stir until fully blended.

Step 3: Assemble the Mac and Cheese

1. Preheat oven to 350°F (175°C) and grease a large baking dish.
2. In a small bowl, whisk the eggs, then temper them by adding a few spoonfuls of the warm cheese sauce while stirring continuously.
3. Pour the cooked pasta into the cheese sauce, mixing until evenly coated.
4. Gently fold in the tempered eggs to create the custard-like consistency.
5. Transfer half of the mixture into the baking dish, then sprinkle a layer of cheddar and gouda on top.
6. Add the remaining mac and cheese mixture and finish with another layer of shredded cheese.

Step 4: Bake to Perfection

1. If using breadcrumbs, mix them with melted butter and sprinkle evenly over the top.
2. Bake uncovered for 30-35 minutes, or until the edges are bubbling and the top is golden brown.
3. Remove from the oven and let rest for 5-10 minutes before serving.