1(24-ounce) jar good-quality tomato pasta sauceI like roasted garlic or tomato basil
1tablespoonred wine vinegar
1(10-ounce) pack frozen spinachdrained and pressed as dry as possible
1cuppart-skim ricotta cheeseor low-fat 1% or 2% cottage cheese
1cupshredded fontina, mild provolone, mozzarella, or similar melty cheesedivided
1/4cupgrated Parmesan cheese
Chopped fresh parsley
Place a rack in the center of your oven and preheat the oven to 400 degrees F. Roast the spaghetti squash according to this recipe for Roasted Spaghetti Squash.
While the squash is baking, heat the remaining tablespoon oil in a large skillet over medium high. Add the turkey, 1 teaspoon salt, remaining 1/2 teaspoon pepper, Italian seasoning, and red pepper flakes. Stir and cook, breaking apart the meat into small pieces, until it is fully cooked through and browned on all sides, about 4 minutes. Stir in the garlic and cook until fragrant, about 1 minute more. Reduce the heat to low. Stir in the pasta sauce and red wine vinegar. Let simmer 1 minute. Taste and adjust the seasoning as desired.
Place the spinach in a large mixing bowl. Use a fork to separate any large clumps. Add the ricotta, 1/2 cup fontina, and remaining 1/2 teaspoon salt. Stir with the fork to combine. When the squash is cool enough to handle, use a fork to fluff the insides into strands and add the strands to the bowl. With the same fork, stir to combine, evenly distributing the ingredients as best you can. Return the squash halves to the baking sheet, cut sides up.
Fill the squash: Pile the ricotta/squash filling evenly into each of the four halves. Top with tomato sauce, remaining shredded cheese, and Parmesan. Return to the oven and bake until the filling is fully heated through and the cheese is melty, about 10 to 15 minutes.
Brown the top (optional): Turn the oven to broil. Broil the squash until the cheese is extra bubbly and lightly browned, about 2 minutes. Watch it carefully, and do not walk away so that it doesn't burn. Sprinkle with parsley and enjoy!
TO STORE: Place cooked and cooled spaghetti squash lasagna in an airtight storage container in the refrigerator for up to 3 days.
TO REHEAT: Gently rewarm leftovers in the oven at 350 degrees F until heated through. You can also reheat leftovers on a microwave-safe plate in the microwave until warm.
Depending upon how much sauce you like, you may have extra. You can freeze the leftovers or use them later in the week over pasta or on spiralized noodles.