In a dutch oven or deep skillet, place chopped onion, minced garlic, and three diced roma tomatoes into the pot. Top with one tablespoon olive oil. Saute on medium heat until onions are tender.

Start the water for the pasta. Bring to a boil. Cook as directed on box.

Add butter to the tomato mixture. Melt butter. Add heavy whipping cream and bring to a low boil. Reduce heat and cook for about 10 minutes until thickened. Add in parmesan and stir well until parmesan is melted.

Drain pasta.

Add in the remaining three diced roma tomatoes and basil to the pot. Salt, pepper, and stir. Add spaghetti and toss well. Serve with bread.