Bring a large pot of water to a boil to cook the pasta.
While the water is heating up, add olive oil to a large pan/skillet.
Once the oil is hot, add crumbled sausage. Brown the sausage for 3-4 minutes. Break any big lumps of meat with the spatula.
Add diced onion and garlic to the browned sausage. Saute for a minute.
Then add tomato paste, crushed fennel, Italian seasoning, and red pepper flakes. Cook for another minute and let the tomato paste caramelize.
Deglaze the pan with wine and scrap the bottom of the pan to release any brown bits. Let the wine cook to half the quantity and you can't smell the alcohol anymore.
Add tomatoes, salt, sugar, and pepper. If using whole tomatoes, break them with the help of a spatula. Reduce heat, cover, and let it cook for 5-6 minutes.
By now the water would have come to a boil. Add salt to it. Cook pasta as per pacakge instruction. Drain the pasta and reserve 1 cup of pasta cooking water.
The tomato meat sauce would have come together by now and you can see a thin layer of fat on the top. Check the seasoning and add more salt/sugar/pepper as per taste. (remember the pasta cooking water that we will add in the next step also has salt in it).
Toss in the cooked pasta along with 1/2 cup of pasta cooking water. Add roughly torn Italian basil leaves and finely grated parmesan cheese. Give everything a good mix.