Preheat your oven to 400°F (200°C) and grease a 9x13-inch baking dish with olive oil or cooking spray.

In a large pot, bring salted water to a rolling boil. Add pasta and cook slightly under al dente, then drain.

Heat olive oil in a skillet. Season chicken with salt and pepper, add to skillet and sauté for 5-7 minutes.

In the same skillet, melt butter, add garlic and sauté for 1-2 minutes. Pour in heavy cream and whole milk, simmer for 3 minutes.

Stir in basil pesto and Parmesan cheese until the sauce is smooth.

In a mixing bowl, combine pasta and chicken, pour pesto sauce over and mix in spinach if using.

Transfer mixture to the baking dish, top with mozzarella and Parmesan.

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

Allow to rest for 5 minutes before serving.