Preheat the oven to 400 degrees. Line a rimmed baking sheet with foil for easy clean up.
Place the tomatoes, ½ tablespoon extra-virgin olive oil, ½ teaspoon kosher salt and ½ teaspoon pepper on the baking sheet and toss with your hands or a spatula to coat the tomatoes.
Roast the tomatoes for 10 minutes, or until they are softened. Remove from the oven and set aside.
While the tomatoes are roasting, place a deep skillet over medium heat with the remaining 1 ½ tablespoon of oil. You could alternatively cook this in an electric skillet.
Season both sides of the 4 pieces of chicken with salt and pepper. When the oil is hot, saute both sides of the chicken breast until nicely browned and just cooked through. A thermometer should register 165 degrees. Remove the chicken from the skillet and cover loosely.
Maintaining the heat, add the shallots and lightly sauté and soften, but not brown, only about 1 to 2 minutes.
Add the marinara, peppers, and sun-dried tomatoes. Stir well and bring up to a gentle boil.
Add the spinach leaves, garlic, and crushed red pepper flakes if using. Stir to wilt the spinach and combine.
Add the drained pasta to the marinara mixture and stir gently, but thoroughly.
Add the heavy cream, roasted tomatoes, and basil if using and stir gently again.
Taste for seasoning and adjust as desired.
To serve, slice the chicken breasts and place on top of warm pasta. Top with grated Parmesan cheese if desired.