Bring 4 cups water and 1 tsp kosher salt to a rolling boil in a medium pot. Add 1.75 cups elbow macaroni and cook until just shy of al dente (about 7–8 minutes depending on pasta). Reserve 1/4 cup of the pasta cooking water, then drain pasta and set aside.

Make roux

In the same pot over medium heat, melt 2 tbs unsalted butter. Once melted and bubbling slightly, add 2 tbs all-purpose flour and whisk continuously for 1–1.5 minutes until the raw flour smell is gone and the mixture is pale and bubbling (do not let it brown).

Add milk and cream

Slowly pour in 1.5 cups whole milk and 1/4 cup heavy cream while whisking to avoid lumps. Bring to a gentle simmer and cook, whisking often, until the sauce thickens enough to coat the back of a spoon, about 3–5 minutes.

Finish cheese sauce

Reduce heat to low. Add 2 tbs softened cream cheese and whisk until fully incorporated. Stir in 1/2 cup mild cheddar and 1.5 cups sharp cheddar, a handful at a time, allowing each addition to melt before adding more. Add 1/2 tsp Dijon mustard, 1/4 tsp Worcestershire sauce, 1/4 tsp ground black pepper and 1/8 tsp ground nutmeg (if using). Taste and adjust seasoning with salt to taste. If sauce is too thick, whisk in up to the reserved 1/4 cup pasta water, 1 tablespoon at a time, to reach a creamy pourable consistency.

Combine pasta and sauce

Fold the drained pasta into the cheese sauce until evenly coated. Keep over very low heat just long enough to warm through, about 1–2 minutes. Remove from heat.

Portion to quart

Transfer the mac-n-cheese into a quart container while hot. This recipe yields one quart (serving size as noted).

Optional Topping / Finish (for crusted or baked finish)

Prepare topping

If you want a baked/crusted finish, combine 1/4 cup panko breadcrumbs, 1 tsp melted butter and 1 tbs grated Parmesan in a small bowl until crumbs are evenly coated.

Bake (optional)

Preheat oven to 375°F (190°C). Spread the mac-n-cheese in an ovenproof quart dish, sprinkle the breadcrumb mixture evenly on top, and bake for 12–15 minutes until the topping is golden and the edges bubble. For an extra golden top, broil 1–2 minutes watching carefully.

Garnish and serve

Remove from oven, let rest 3–5 minutes, then sprinkle with 1 tsp chopped fresh parsley before serving.