Cut each squash in half, brush with olive oil and bake for 30 minutes or until tender.
In a saute pan, add olive oil and saute the garlic. Add the spinach and let cook until the leaves are wilted and no liquid remains. Season with salt and pepper. Add the heavy cream, ricotta and Parmesan. Mix well.
Scrape out the insides of the squash and place in a mixing bowl. Add the cheese sauce and stir to combine. Divide mixture among the squash halves and top with mozzarella cheese.
Bake for 10 minutes until cheese is brown and bubbling.