Start by placing a medium to a large pan over medium-high heat, then add the olive oil.
Once the oil is ready, add the minced garlic and onions, and cook until they turn soft.
Add the carrots and celery and cook for 2 to 3 minutes.
Remove the Italian sausage from its casings and add them to the pan.
Cook for a few minutes, just enough for the meat to turn less pink and to separate them.
Pour the crushed tomatoes, add the dried herbs, and season with salt and pepper.
Cover the pan with a lid and simmer for 25 to 30 minutes (Note: keep tasting and adjusting the seasoning in this process). Take the Italian sausage pasta sauce out of the heat and set aside.
Prepare the penne pasta as per the package instruction, then drain. See helpful tips below for suggested cooking time.
Preheat your oven to 180°C (350°F).
Combine the cooked penne and a third of the Italian sausage pasta sauce in a bowl.
Place half of the sauced penne into a baking dish.
Add more sauce on top, about half of the remaining meat sauce.
Add some mozzarella and Parmigiano Reggiano, then repeat by adding the sauced pasta, and so on.
Finish by adding the two types of cheese on top.
Place the penne with Italian sausage in the lower part of the oven for 30 to 35 minutes or until the top turns golden.
Set aside for at least 20 minutes.
Your baked penne pasta with Italian sausage is now ready for serving --- enjoy!