Preheat oven to 375 F (190 C). Cook pasta in salted boiling water until al dente. Drain and set aside.

In a large skillet, heat olive oil over medium-high heat. Add diced chicken and cook until browned and cooked through, about 5-7 minutes. Remove and set aside.

In the same skillet, saute shallot and garlic until fragrant. Stir in cherry tomatoes and cook until slightly softened.

Lower heat to medium-low. Pour in heavy cream and basil pesto, stirring well to combine. Let simmer for 2-3 minutes.

Stir in fresh spinach and Parmesan cheese, cooking until the spinach wilts. Add the cooked chicken and pasta back into the skillet, tossing to coat in the sauce.

Transfer the mixture to a greased baking dish. Top with shredded mozzarella cheese. Bake for 15-20 minutes until the cheese is melted and bubbly. Serve hot.