Brown Sausage: Heat 1 Tbsp. olive oil in a Dutch oven or other heavy-bottomed pot over medium. Add sausage, pressing it into a thin layer that covers the bottom of the pot. Cook, undisturbed, until golden brown on the bottom, about 5 minutes. Flip the sausage and break it up into bite-size pieces, then cook until golden brown all over, stirring occasionally, about 4 to 5 minutes more. Transfer sausage to a bowl.
Sauté Aromatics: Add an extra drizzle of olive oil to the pot (if needed) so there is enough fat to lightly coat the bottom (you should have some residual fat from the sausage). Add onion and sauté until softened, about 4 to 5 minutes. Add the garlic and stir for 30 seconds to 1 minute, until fragrant.
Build Broth: Add tomato paste, dried oregano, and red pepper flakes; cook, stirring to coat, until the tomato paste deepens in color, about 2 minutes. Add Sungold tomatoes and season mixture with kosher salt and a few grinds of black pepper. Cook until the tomatoes are very soft and easily burst, about 8 to 10 minutes. Use the back of a wooden spoon or spatula to press the tomatoes against the side of the pot until all the tomatoes are broken down and jammy.For a smoother broth: if the tomatoes haven't broken down, or you prefer a smoother consistency, add 1 to 2 cups of the broth and use an immersion blender to partially blend the tomato mixture. (I tested the soup with and without blending the tomatoes and enjoyed it equally both ways.)Add sausage back to pot and stir to combine. Boil Noodles: Add the chicken broth and bring to a boil over high heat. Stir in the noodles, reduce the heat and simmer, uncovered, stirring occasionally, until the noodles are tender and the broth has reduced slightly, about 15 to 20 minutes.
Prepare Ricotta Mixture: While the soup simmers, combine the ricotta and Parmesan in a medium bowl. Add a few grinds of black pepper and mix well; set aside
Mix Pesto Oil: Add pesto to a small bowl and gradually mix in olive oil until the consistency is thin enough to drizzle.
Finish Soup: Once the soup has simmered and the noodles are tender, turn off heat and stir in heavy cream and fresh basil. Taste and adjust seasonings as needed. You may need a pinch more salt and/or extra red pepper flakes.
Serve: Ladle the soup into shallow bowls and top with a large dollop of the ricotta mixture, drizzle of pesto oil, and extra fresh basil for garnish.