In a large skillet over medium-low heat, combine the chopped sun-dried tomatoes with 2 tablespoons of the oil reserved from their jar. Cook for 1 minute until fragrant.

Add the chicken pieces to the skillet. Sprinkle with salt and red pepper flakes. Cook over medium heat, stirring occasionally, until the chicken is cooked through and no longer pink, about 5 minutes.

Add the chopped Roma tomatoes, fresh basil, spinach, and minced garlic to the skillet. Cook over medium heat for 3 to 5 minutes, until the spinach is just wilted and the tomatoes begin to release their juices. Remove from heat, taste, and adjust salt if needed. Cover and keep warm off the heat.

Meanwhile, cook the spaghetti according to package directions until al dente. Drain well.

Add the drained pasta to the skillet with the chicken and vegetables. Return to low heat, toss everything together, and cook for 1 to 2 minutes until heated through. Taste and adjust seasoning with salt and pepper if desired.

Remove from heat. Drizzle with the remaining 3 tablespoons of olive oil (or more oil from the sun-dried tomato jar) for extra richness. Serve immediately.