Bring a large pot of water to a rapid boil, then season generously with a few tablespoons of Kosher salt. Add pasta, then cook according to package directions until al dente. Reserve cooking water, then drain pasta in a colander.
Place chicken in a large mixing bowl, then season with dried oregano, Kosher salt, black pepper. Toss well to thoroughly coat.
Heat olive oil over medium-high heat in a large skillet with deep sides. When hot, add seasoned chicken and cook, stirring occasionally, until the chicken is browned on all sides and fully cooked through. Use a slotted spoon to transfer chicken to a plate or bowl.
To the same skillet, heat an additional olive oil in the skillet (or even better sun dried tomato oil). When hot, add chopped basil, then cook, stirring occasionally, until very fragrant. Add chopped garlic cloves, sun dried tomatoes, and crushed red pepper flakes, then stir and cook
Add tomato paste, then use a spoon to break up and dissolve. Add white wine, then allow to cook off for 1-2 minutes. Pour in heavy cream, then use the spatula to scrape the bottom of the pan and stir well.
Add the cooked, drained pasta to the sauce, along with the chicken, spinach, reserved pasta water, and grated Parmesan. Stir well. Serve in large bowls with additional grated Parmesan and basil leaves. Sprinkle each bowl with a pinch of flaky sea salt!