Preheat oven to 375. Drizzle olive oil on a baking sheet. Spread the butternut squash slices on a baking sheet, flip over so each side has a touch of oil. Place the acorn squash halves on a separate baking sheet. Roast all of the squash for 25-35 minutes until tender.
Make sure the spinach is drained well and then combine it with the garlic and ricotta cheese.
Make the bechamel sauce. Warm the milk in a saute pan or in the microwave. Melt the butter into a saucepan over medium heat. Sprinkle in the flour and whisk over the heat until it becomes a light golden paste. Drizzle in the milk slowly, while whisking rapidly and simmer until it becomes a thick sauce.
When the acorn squash is done, scoop it out and puree it in a food processor or blender, slowly add in half of the bechamel sauce until it becomes smooth.
To layer the lasagna, start with about a 1/2 cup of the white sauce on the bottom. Layer in the pasta noodles, spread on a layer of the spinach ricotta mixture, layer on the squash slices, pour on the squash sauce. Layer on more pasta and repeat until the lasagna is complete. Finish with the white sauce and a sprinkle of the mozzarella cheese.
You can cover and store this until about an hour before dinner. Bake, covered with foil at 375 for 35-45 minutes until the center is hot to the touch. Remove the foil and bake for 5 more minutes until the top is lightly golden.
