Bring a large pot of salted water to a boil. Add the 12 oz penne pasta and cook according to package instructions until al dente, usually around 9-11 minutes. Drain and set aside.
Heat 2 tablespoons of olive oil in a large skillet over medium heat. Add the sliced chicken sausage and cook until browned on both sides, about 5-7 minutes. Remove the sausage and set it aside.
In the same skillet, add the minced garlic and sauté for 1 minute until fragrant. Toss in the halved cherry tomatoes and chopped spinach. Cook for 2-3 minutes until the spinach wilts and tomatoes soften slightly.
Lower the heat and pour in 1 cup of heavy cream. Stir in the 1 teaspoon of Italian seasoning, salt, and pepper to taste. Allow the cream to warm and thicken slightly for 2-3 minutes. Gradually stir in 1 cup of grated Parmesan cheese until melted and smooth.
Return the browned sausage slices to the skillet and mix everything thoroughly. Add the drained penne pasta and toss gently so that the creamy sauce coats all ingredients evenly.
Preheat your oven to 375°F (190°C). Transfer the pasta mixture into a greased 9x13-inch baking dish. Sprinkle 1 cup of shredded mozzarella cheese evenly over the top. Bake uncovered for 15-20 minutes or until the cheese is melted, bubbly, and slightly golden.
Remove the pasta bake from the oven and let it rest for 5 minutes. Garnish with fresh basil leaves. Serve warm and enjoy.