Ingredients
1/2 c. (1 stick) butter, plus more for baking dish
1 lb. elbow macaroni
1/2 c. flour
5 c. whole milk
1 1/2 tsp. kosher salt
Freshly ground black pepper
1 tsp. mustard powder
3 c. shredded cheddar
2 c. shredded Gruyère
1 1/2 c. grated Parmesan, divided
1 c. panko bread crumbs
3 tbsp. extra-virgin olive oil
Freshly chopped parsley, to garnish
Preparation
Step 1Preheat oven to 375°. Butter a 9”-x-13” baking dish. In a large pot of salted, boiling water, cook macaroni until al dente. Drain and set aside.Step 2In a large saucepan, melt 1 stick butter. Sprinkle over flour and cook until slightly golden, 2 to 3 minutes. Pour in milk and whisk until combined. Season with mustard powder, salt, and pepper. Let simmer until starting to thicken, about 5 minutes. Step 3Remove pan from heat and whisk in cheddar, Gruyère, and 1 cup Parmesan. Continue whisking until melted and smooth. Stir in cooked macaroni and transfer to prepared baking dish. Step 4In a small bowl, combine remaining Parmesan with Panko and oil. Sprinkle mixture over macaroni, then season with more black pepper. Step 5Bake until bubbly and golden, 25 to 30 minutes. Step 6Garnish with parsley before serving. Let sit 10 minutes before serving.
