Cook the pasta in a large pot of salted water according to package directions. Drain the pasta.
While the pasta is cooking, heat a large skillet over medium high heat. Place some paper towels on a clean plate. Add the pancetta and cook, stirring occasionally, until it is crispy, about 5 minutes. Transfer with a slotted spoon to the paper towels.
In the pot that you cooked the pasta in, combine the marinara sauce, basil, oregano and salt and pepper. Add the pasta and toss to combine. Add 1 cup of the mozzarella, the fontina, Parmesan and pancetta, and toss until everything is evenly combined.
Transfer half of the pasta to a shallow 3 or 4-quart baking dish and spread it out evenly. Use a tablespoon to dollop the ricotta in little mounds across the surface. Spoon the rest of the pasta on top in an even layer. Sprinkle the remaining 1 cup mozzarella over the top.
Bake the casserole for about 30 minutes until everything is hot and the cheese is melted and the top is golden brown. Sprinkle with the slivered fresh basil and serve hot.
Notes
You can make this casserole ahead of time and keep it covered in the fridge for up to a day. Then bake it when you are ready, adding another 5 to 10 minutes to the baking time if you are taking it straight from the fridge and putting it into the oven still cold.