Preheat the Oven:
Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper or lightly grease it to prevent sticking.
Prepare the Spaghetti Squash:
Carefully cut the spaghetti squash in half lengthwise. Use a spoon to scoop out the seeds and stringy pulp from the center. Drizzle the cut side of each half with olive oil and season lightly with salt and pepper. Place the squash halves cut side down on the prepared baking sheet.
Roast the Squash:
Roast the spaghetti squash in the preheated oven for 25-30 minutes, or until the flesh is tender and easily shreds with a fork. Once done, remove from the oven and let it cool slightly. Use a fork to scrape the squash into spaghetti-like strands. Reduce the oven temperature to 375°F (190°C).
Cook the Meat Sauce:
While the squash is roasting, heat a large skillet over medium heat. Add the ground beef or Italian sausage and cook until browned, breaking it into small pieces with a spatula.
Drain any extra grease. Then, stir in the marinara sauce, garlic powder, Italian seasoning, and a little salt and pepper. Simmer for 5-7 minutes to let the flavors meld.
Assemble the Casserole:
In a mixing bowl, combine the ricotta cheese, 1 cup of shredded mozzarella cheese, and grated Parmesan cheese. Mix well.
In a greased 9x13-inch baking dish, layer half of the shredded spaghetti squash. Next, add half of the meat sauce.
Finally, top with half of the cheese mixture. Repeat the layers, ending with the remaining meat sauce. Sprinkle the top with the remaining ½ cup of shredded mozzarella cheese.
Bake the Casserole:
Bake in the oven at 375°F (190°C) for 20-25 minutes, or until the cheese is melted and bubbly. For a golden-brown top, broil for an additional 2-3 minutes, keeping a close eye to prevent burning.
Serve and Enjoy:
Remove the casserole from the oven and let it cool for 5-10 minutes. Garnish with fresh basil or parsley if desired. Slice into portions and serve warm. This gluten-free, low-carb squash lasagna casserole is perfect for a cozy keto dinner!