Heat the olive oil in a large non-stick pan over medium heat.
Once hot, add the onions and garlic and cook until fragrant.
Add the canned tomatoes and bring it to a boil.
Once boiling, reduce the heat to low and let the sauce simmer for 30 minutes.
Add the salt, pepper, sugar, and Italian seasoning and stir for a further minute or two.
Using a hand or stick mixer, blend the sauce until completely smooth.
Cook the pasta as per the package instructions.
Drain and reserve ¼ cup of pasta water.
Add the pasta to the sauce, along with the pasta water, and simmer for 5 minutes.
