Preheat oven to 375 degrees.
Line a baking sheet with parchment paper (or aluminum foil sprayed with cooking spray).
Cut spaghetti squash in half lengthwise and remove seeds.
Place spaghetti squash on baking sheet and pierce it several times with a fork to vent. Bake for 30 - 40 minutes for firmer “noodles” or 60 minutes for softer noodles, depending on preference.
Reduce oven temperature to 350 degrees and let the spaghetti squash cool for about 20 minutes.
Use a fork to scrape the spaghetti squash into stringy noodles.
Lightly coat a 4-quart baking dish with cooking spray.
Spread a light coat of marinara sauce on bottom of baking dish. Evenly layer half of the spaghetti squash in the dish and pour half of the marinara sauce on top.
Spoon half the ricotta cheese on top and gently spread it evenly over the marinara sauce.
Lay half of the lasagna noodles on top.
Repeat the layers (spaghetti squash, marinara sauce, ricotta cheese, then lasagna noodles), but this time reserve about half a cup of marinara sauce.
Top the lasagna noodles with the remaining marinara sauce, then top with parmesan cheese.
Bake for 30 minutes, or until golden brown and bubbly.
Garnish with basil.
Enjoy!