Pasta: Bring the pasta water to a boil. Add salt and pasta. Cook al dente (according to packet instructions). Drain when cooked.
In the meanwhile, make the sauce.
Chop the shallot and the garlic finely. If using fresh tomatoes, chop them (you can peel them first if desired – Note 3). Set aside separately.
Heat the oil in a saucepan and cook the chopped onions and garlic until they are softer about 3 minutes. Add tomatoes, tomato paste, herbs, sugar, a little salt, and pepper. Stir well. Bring to a boil, turn the heat down and simmer gently for 15 minutes.
Add mascarpone and balsamic vinegar, stir well and simmer for another 2 minutes. Adjust the taste with more balsamic vinegar, salt, and pepper. Remove the basil leaves, add the remaining fresh chopped ones.
Mix the mascarpone sauce with the cooked pasta.
Sub with about 2 teaspoons dried Italian herbs or a mixture of dried oregano, thyme, and rosemary.
Sub with the same amount of full-fat cream cheese.
Blanch the tomatoes in the boiling pasta water before adding the salt and before cooking the pasta. After removing the blanched tomatoes with a slotted spoon, you can use the water for cooking the pasta. First, wash the tomatoes and slice a shallow X into their bottoms. Then, carefully place the tomatoes into the boiling water, about 3 or 4 at a time. Boil them for about 25 seconds, no longer, or they will begin to soften. Remove with a slotted spoon and rinse under cold water (or you can place them in a bowl of ice water). Next, remove the peel with a small knife starting at the X and pulling the skin back. You can now start cooking the pasta in the same water.