Preheat your oven to 375°F (190°C) and grease a 9x13 casserole dish.

In a large pot, bring salted water to a boil, add cavatappi pasta, and cook until al dente (7–9 minutes). Drain.

Melt butter in a large skillet over medium-low heat and stir in half of the seasoning mix.

Add flour to the skillet and whisk to combine; cook for 1–2 minutes.

Slowly whisk in evaporated milk and heavy cream, bringing to a gentle boil.

Add remaining seasoning mix and Dijon mustard to the mixture; simmer for 2–3 minutes.

Gradually add half of the mixed cheeses, stirring until melted and smooth.

Fold the cooked pasta into the cheese sauce until well-coated.

Layer half of the macaroni mixture in the greased casserole dish, sprinkle with cheese, then add remaining macaroni and top with cheese.

Bake for 30 minutes, then broil for an additional 3–4 minutes for a crispy topping.

Let the casserole cool for a few minutes before serving.