This is a recipe that I I have made in the past and just came across. It comes from Giada De Laurentis, with a few minor changes from me. It's fairly quick and simple and tastes great. Plus it's a little something different than typical red sauce baked pastas.
Baked Rigatoni with Bechamel Sauce
1 stick unsalted butter
1/2 cup + 2 Tbsp. all-purpose flour
1 qt. whole milk at room temperature
Pinch fresh nutmeg
Sea salt and white pepper
1 cup grated fontina
1/2 lb. thinly sliced prosciutto, julienned
8 oz. sliced cremini mushrooms
1/2 tsp. crushed red pepper flakes
1 lb. dry rigatoni
3 Tbsp. unsalted butter, diced
Preheat oven to 425 degrees.
In a 2 qt. saucepan, melt butter over medium heat. Add flour and whisk until smooth, about 2 minutes. Always stirring, gradually add milk and whisk until smooth and creamy. Simmer until thick enough to coat the back of spoon, about 10 minutes. Remove from heat and stir in nutmeg, 1/2 cup fontina, prosciutto, mushrooms, salt and peppers. Set aside.
Cook pasta in large pot of boiling salted water. Add pasta and cook for about 5 minutes. You want the pasta a little hard since you are cooking a second time in oven. Drain, return to pot and add sauce. Mix well until pasta is coated with sauce.
In a greased 13x9 baking dish, pour pasta. Smooth out top and sprinkle with remaining cheese. Sot with diced butter and bake 25 minutes or until bubbling and golden brown.