Cook pasta according to package directions. Drain well.
Meanwhile, in a small bowl combine the basil, garlic powder, rosemary, salt and pepper and set aside. Place 3 tablespoons of flour in a shallow dish and add 1 tablespoon of the seasoning mixture. Reserve the remaining seasoning mixture for later.
Coat the bottom of a large skillet with olive oil and place over MEDIUM-HIGH heat. Lightly dredge the chicken in the seasoned flour, shaking off the excess, and add it to the pan. Cook for about 3 to 4 minutes per side, or until golden brown and cooked through. Cook in batches if necessary. Remove the chicken from the skillet and keep warm. Discard any remaining seasoned flour mixture.
Add a little more olive oil to the skillet and return it to MEDIUM heat. Add the onion and cook and stir for about 3 minutes until softened. Add the minced garlic and cook, stirring for another minute. Stir the tomato paste into the skillet then add the diced tomatoes, broth, and the reserved seasoning mixture.
Stir remaining 2 teaspoons flour into the half and half and mix until completely smooth. Add the mixture to the skillet. Bring the sauce to a simmer, stirring occasionally. Add the red pepper flakes (if using). Reduce heat to LOW, return the chicken to the skillet, and cook until heated through. Garnish with fresh herbs, if using.
Serve the chicken and tomato sauce over the cooked pasta with Parmesan cheese.