I downloaded this recipe from foodnetwork.com originally and eventually ended up adding more traditional lasagna ingredients to it. It is absolutely fantastic! Hope you will give it a try! Even my grandgirlies like it! I am going to try it with Pumpkin and also Acorn Squash as well.
Heat the oil in a heavy large skillet over medium-high heat. Add the squash and toss to coat. Sprinkle with salt and pepper. Pour water into skillet and then cover and simmer over medium heat until the squash is tender. About 20 minutes.
Cool slightly and then transfer the squash into a food processor. Puree squash. (I did this method and I have also used already pureed squash I had in the freezer.)Once pureed, set aside.
Brown your ground beef and set aside.
Melt the butter in a heavy medium size saucepan over medium heat. Add the flour and whish for one minute. Gradually whisk in the milk. Bring to a boil over medium-high heat. Reduce heat to medium and simmer until the sauce thickens slightly, whisking often, about 5 minutes. Whisk in nutmeg.
Cool the sauce slightly and transfer half of the sauce to a blender. (Please note~when blending hot liquids, remove liquid from the heat and allow to cool for 5 minutes. Transfer liquid to blender and fill no more than halfway. When using blender, release one corner of the lid. This prevents the vacuum effect that creates heat explosions. Place a towel over the top of the machine, pulse a few times then process on high speed until smooth.)
Add the basil and blend until smooth. Return the basil sauce to the sauce in the pan and stir to blend. Season with salt and pepper to taste.
At this point I blended my Ricotta cheese with my squash puree.
Preheat your oven to 375 Degrees and be sure the rack is in the center position in the oven.
Lightly butter a 9"x13" glass baking dish. Spread 3/4 cup of the sauce over the prepared baking dish.
Arrange lasagna noodles on the bottom of the pan. Spread 1/3 squash/ricotta puree over the noodles. Spread 1/3 of the browned ground lean beef over the squash puree. Sprinkle with 1/3 of mozzarella cheese. Repeat layering 2 to 3 more times. Be sure to spread 1/2 cup of the sauce over the additional layers of lasagna noodles before layering the squash and ground beef.
Tightly cover the baking dish with foil and bake for 40 minutes. Sprinkle the remaining mozzarella and parmesan cheese over the lasagna. Continue baking uncovered until sauce bubbles and top is golden brown. About 15 minutes longer. Let stand for 15 minutes before serving.