Bring a large pot of salted water to a boil. Add 12 oz penne pasta and cook according to package instructions until al dente, about 10-11 minutes. Drain and set aside, reserving about ½ cup of pasta water.
Heat 2 tablespoons olive oil in a large skillet over medium-high heat. Add the diced chicken breast, seasoning with salt and pepper. Cook until browned and cooked through, about 5-7 minutes. Remove chicken from the skillet and set aside.
In the same skillet, reduce heat to medium. Add minced garlic and sauté until fragrant, about 1 minute. Toss in the halved cherry tomatoes and cook for 2-3 minutes until they soften and release their juices.
Add 1 cup fresh spinach and stir until it wilts, roughly 1-2 minutes. Pour in 1 cup heavy cream and sprinkle 1 teaspoon Italian seasoning. Stir to combine and bring the sauce to a gentle simmer.
Slowly add 1 cup grated Parmesan cheese, stirring constantly until melted and the sauce thickens. Return the cooked chicken to the skillet and stir to coat with the creamy sauce. If the sauce is too thick, add a splash of reserved pasta water to loosen it.
Add the cooked penne pasta into the skillet with the sauce and toss gently to combine everything evenly. Taste and adjust seasoning with salt and pepper as needed.
Serve the Creamy Tuscan Chicken Penne hot, garnished with fresh basil leaves for a pop of color and aroma. Pair it with a side salad or garlic bread for a complete meal.