1 pound casarecce or fusilli or shell pasta
1/2 pound prosciutto, thinly sliced
1 quart whole milk or heavy cream, room temperature
1 1/2 cups fontina or Gruyere cheese, grated
1/2 cup parmesan cheese, grated
1/2 cup all-purpose flour
1/2 cup (1 stick) unsalted butter
1 pinch freshly grated nutmeg
kosher salt and freshly ground pepper, to taste

Preparation

Preheat oven to 400º F and lightly grease a 9x13-inch baking dish.
Bring a large pot of salted water to boil and cook pasta until just al dente. (Don't overcook.) Drain and set aside.
In a large saucepan over medium heat, melt better. Sprinkle flour into butter and whisk mixture for until smooth, with no remaining lumps. About 2 minutes.
Continue to stir and slowly add milk or cream to butter flour roux. Whisk until smooth and creamy.
Cook bechamel for 8-10 minutes, or until thickened.
Once thick, remove from heat and season with nutmeg, cheeses (reserve 1/2 cup fontina), prosciutto, salt and pepper.
Return pasta to pot and pour prosciutto and bechamel sauce over the top. Stir so that everything is thoroughly coated.
Pour pasta into baking dish and top with remaining fontina. Bake for 25-30 minutes, or until cheese is bubbly and golden brown.
Remove from oven and serve hot.