Preheat oven to 400.

Toss butternut squash and sage leaves with olive oil (just enough to coat) and sprinkle with salt, pepper, and nutmeg. Place on foil lined baking sheet.

Bake for about 20 minutes, until golden brown and easily pierced with a fork.

While squash is baking, make the garlic parmesan sauce. To do this, melt the butter on a skillet on medium heat. Add garlic and cook until fragrant (2-3 minutes), then add flour and mix until incorporated and browned. Slowly mix in milk until sauce is lump free. Add half and half and parmesan, and mix until sauce is formed. If sauce is too thick, add more milk. Salt and pepper to taste. Remove from heat.

Mix together ricotta, parmesan, and spinach in a medium bowl. When butternut squash is done, remove sage leaves and set aside. Mix butternut squash with ricotta mixture.

In an 8x8 pan, spread half of the garlic parmesan sauce. Evenly distribute butternut squash mixture between shells., and place in pan on top of sauce. Pour the rest of the sauce on top of shells.

Bake for about 20 minutes, until heated through and top is slightly browned.

Remove from oven, garnish with baked sage leaves, and serve.