Bring a large pot of salted water to a boil and cook 10 ounces fettuccine (or pasta of choice) until al dente according to package directions; drain and set aside.
While the pasta cooks, heat 2 tablespoons extra virgin olive oil in a large skillet over medium-high heat.
Add the diced yellow onion and sauté until tender and translucent, about 5 minutes.
Add the minced garlic and cook 1 minute until fragrant.
Add the cubed chicken breast and cook, stirring occasionally, until the chicken is no longer pink and cooked through.
Stir in the diced tomato and cook 1 minute to warm through.
Pour in the cup of half-and-half mixed with 1 tablespoon flour, then add 3 tablespoons sun-dried tomato pesto and 1/2 teaspoon salt; stir to combine.
Bring the sauce to a gentle boil, then reduce heat to low, cover, and simmer for 5 minutes, stirring occasionally to thicken.
Add the drained pasta to the skillet and toss well to coat with the sauce.
Toss in the fresh basil leaves, season with freshly ground black pepper to taste, and serve immediately with grated Parmesan cheese.