Preheat your oven to 400°F (200°C). Lightly grease a 9x13-inch baking dish.

Bring a large pot of salted water to a boil. Add pasta and cook for 2 minutes less than package instructions. Drain.

In a large skillet, heat olive oil. Season chicken with salt and pepper, sauté for 5-6 minutes until fully cooked. Set aside.

In the same skillet, melt butter over medium heat. Sauté minced garlic until fragrant. Pour in heavy cream and whole milk, simmer until thickened.

Stir in basil pesto and grated Parmesan until well combined and smooth.

In a large bowl, combine cooked pasta, sautéed chicken, and spinach. Pour creamy pesto sauce over, tossing gently until coated.

Transfer mixture to the greased baking dish. Top with shredded mozzarella and sprinkle extra Parmesan.

Bake uncovered for 20-25 minutes until cheese is golden and bubbly.

Let rest for 5 minutes before serving to allow layers to settle.