01 - Bring a large pot of salted water to a boil. Cook pasta according to package directions until al dente. Reserve ½ cup pasta water, then drain.
02 - In a food processor, blend basil, pine nuts, garlic, Parmesan, lemon juice, and a pinch of salt and pepper. Slowly drizzle in olive oil until a smooth pesto forms. Adjust seasoning to taste.
03 - Heat 1 tablespoon olive oil in a large skillet over medium heat. Add chicken pieces and cook 6-7 minutes, stirring occasionally, until golden and cooked through. Season lightly with salt and pepper. Transfer to a plate.
04 - Add cherry tomatoes and spinach to the skillet and sauté 2 minutes until just softened, if using.
05 - Reduce heat to low, return chicken to the skillet, and add drained pasta. Stir in pesto and a splash of reserved pasta water to create a light sauce that coats the pasta. Serve immediately, garnished with extra Parmesan and basil.