Bring a large pot of salted water to a boil. Add the penne pasta and cook according to package instructions until al dente, usually about 10-12 minutes. Drain the pasta and set aside, reserving a little pasta water for later if needed.
Heat the olive oil in a large skillet over medium-high heat. Add the diced chicken breast and season with salt, pepper, and half of the Italian seasoning. Cook until golden brown and cooked through, about 5-7 minutes. Remove the chicken from the skillet and set aside.
In the same skillet, add the minced garlic and sauté for about 30 seconds until fragrant. Pour in the chicken broth and bring to a simmer, scraping any browned bits from the bottom of the pan to incorporate that deep flavor.
Lower the heat and stir in the heavy cream, sun-dried tomatoes, and remaining Italian seasoning. Let the sauce simmer gently for 3-4 minutes until it thickens slightly.
Return the cooked chicken to the skillet along with the fresh spinach. Stir until the spinach wilts into the sauce. Add the drained penne pasta and toss everything together until well coated. If the sauce seems too thick, add a splash of reserved pasta water to loosen it.
Turn off the heat and stir in the grated Parmesan cheese until melted and creamy. Taste and adjust seasoning with salt and pepper as needed. Serve hot, garnished with fresh basil leaves for a pop of color and flavor.