Fill a large pot with water, add a generous pinch of salt, and bring it to a boil. Add the 12 ounces of spaghetti and cook according to package directions until al dente (about 8-10 minutes). Drain the pasta, reserving ½ cup of pasta water, and set aside.
While the pasta cooks, heat 2 tablespoons of olive oil in a large skillet over medium-high heat. Season the 4 chicken breasts with salt, pepper, dried oregano, and dried basil. Cook chicken for 5-6 minutes per side until golden brown and internal temperature reaches 165°F. Remove and let rest before slicing.
In the same skillet, add minced garlic and cook for about 30 seconds until fragrant. Add halved cherry tomatoes and sauté for 2-3 minutes until slightly softened.
Add lemon zest and juice to the skillet along with fresh spinach. Stir until spinach wilts. Add reserved pasta water if sauce seems dry.
Return sliced chicken to the skillet, add drained spaghetti, and toss gently to coat pasta with sauce and evenly combine chicken, spinach, and tomatoes.
Serve hot, garnished with chopped fresh parsley and grated Parmesan cheese if desired. Pair with garlic bread for an extra touch.
