Take out each tomato from the San Marzano Tomatoes (1 can) and remove as many seeds as possible. While doing so, crush with hands or potato masher. Transfer to a bowl and strain remaining juice from the can to remove the seed and add to the bowl with the crushed tomatoes. Reserve can with 1/2 c of water.
Heat Olive Oil (2 tablespoon) in a large skillet over medium-high heat. Add the tomatoes and sauce. Bring to a boil and cook until thickened. Reduce the heat and stir in reserved water. Season with Kosher Salt (to taste). Process should take around 30 minutes.
For the oil, heat Olive Oil (1/4 cup) in a small sauce pan over medium-low heat. Once hot, add the Fresh Basil Leaves (3 N/A) [Chiffonade], Crushed Red Pepper Flakes (1 pinch), and Garlic (3 clove). Cook until the garlic has just browned. Remove from heat and strain, reserving the infused oil.
Cook Spaghetti (1 pound) in salted water until al dente. Once nearly finished, add the infused oil into the tomato sauce and combine. Season with Ground Black Pepper (to taste) and more Kosher Salt (to taste).
Once noodles are al dente, lift with tongs above water (allowing water to drip off), and transfer into a new small pan with a ladle of the tomato sauce and Butter (1 tablespoon). Toss noodles and then transfer to a plate.
Serve garnished with Parmesan Cheese (to taste) and Fresh Basil Leaf (3). Enjoy!