In a large non-stick fry pan, heat oil over a medium heat. In low heat, cook onion, until softens. Add the turkey ham and sautéed them a bit, add the chilli flakes and garlic and continue to cook for 2 - 3 minutes. Add the tomatoes, and season with salt and pepper, as desired. Simmer for 20 minutes until the sauce thickens.
Meanwhile, cook the penne according to packet instructions. Drain well and set aside until the sauce is ready.
Once the sauce has thickened, add the penne and stir well to evenly coat the pasta. Transfer to a large baking dish and layer the slice cheese on top. Place in oven and cook for 15 - 20 minutes or until cheese has melted and turns golden brown.
If you find the can of tomatoes a bit too sour-ish to your liking, you can add a bit of sugar to balance back the taste.
To make the dish cheesier, you can add more cheese in between the pasta as well when mixing with the sauce.