From "Tastes of Italia" magazine, March 2005, with substantial edits ("improvements" :-)) by mrm
Preheat oven to 350. Lightly spray a 9 x 12-inch baking dish with cooking spray (you can buy organic olive oil sprays now!) Set aside.
Cook pasta according to package directions. While pasta is cooking, toast the pine nuts in a large skillet over medium heat. Be careful not to burn them, it only takes a couple minutes to toast them. Move pine nuts into bowl and set aside.
Cook Italian sausage until mostly done. I do this by first cooking the whole sausage over medium-high heat, and then when they are halfway done, slicing them into 1/2-inch slices and finishing the job. DO NOT OVERCOOK the sausage. Add olive oil, garlic, pine nuts, salt and red chile pepper flakes. Simmer for 3 or 4 minutes. Add tomato sauce - here, use your judgement as to how much sauce you'd like to have with the pasta. I like a lot of sauce. Some people prefer less sauce. Add oregano. Bring to a boil, then reduce heat and simmer 15 to 20 minutes or until sauce is at the thickness you like. I simmer for less than 10 minutes - this will depend on how thick you like the sauce, and how thick (or thin) it is to start with.
When the pasta is mostly cooked, but perhaps just a bit shy of fully cooked, remove from stove, drain, and pour into prepared baking dish. Stir in butter right away to coat. Add sauce and parmesan cheese and stir well. Top with the other cheese (ricotta or provolone) and place in oven. Cook, uncovered, for 8 to 9 minutes or until cheese melts. Remove and serve.
It wouldn't hurt to leave the dish in the oven longer, if when you taste it, you think the penne need to be cooked more/softened up more. Again, this is according to your taste, and if you prefer pasta al dente or not.
This is great as a leftover, either hot or cold!
Makes 6 servings