Halve spaghetti squash lengthwise and scoop out seeds. Drizzle cut sides with olive oil and sprinkle generously with kosher salt. Place squash cut side down on the baking sheet.

Roast 30–60 minutes, depending on size, until the skin gives easily when pressed and the flesh shreds into strands with a fork.

Using tongs, flip the squash cut side up and let cool for 5–10 minutes until you can handle it safely. Scrape the strands into a medium bowl with a fork. Leave watery liquid behind on the sheet pan if it collects.

Toss squash with a generous drizzle of olive oil, kosher salt, freshly ground black pepper, and freshly grated nutmeg (omit nutmeg if you only have pre-ground). Taste and adjust.

Reduce oven temperature to 350°F.

In a medium bowl, mix ricotta and chopped cilantro until evenly combined. Set aside.

Heat about 1 tablespoon of olive oil in a large skillet over medium heat. Add thinly sliced onion and cook for 5–7 minutes until softened and lightly golden. Add minced garlic and cook for 30 seconds until fragrant. Transfer onion/garlic mixture to a bowl.

Add a little more olive oil if needed and sauté kale 4–5 minutes until wilted and tender. Combine with onions and stir to distribute evenly.

If using dried noodles, cook until al dente according to package directions. Drain, rinse briefly to stop cooking, then toss lightly with olive oil so they don’t stick. (If using fresh sheets, you can usually layer them straight in.)

Spread a thin layer of tomato sauce in the bottom of a 12x7x4-inch baking dish.

Lay 3 overlapping lasagna sheets over the sauce (or enough to cover in a single layer).

Spread about one-third of the ricotta mixture over the noodles.

Add a thick layer of spaghetti squash (about ¾-inch is great), being careful not to scoop in excess liquid from the bottom of the bowl.

Sprinkle one-third of the onion/kale mixture over the squash.

Spoon tomato sauce over the vegetables and spread it evenly.

Sprinkle it with mozzarella and asiago.

Repeat the layering (noodles, ricotta, squash, vegetables, sauce, cheese) until the dish is filled, ending with sauce and cheese on top.

Bake uncovered for about 50 minutes, until bubbling around the edges and lightly golden on top.

Rest 10–20 minutes before slicing so the layers set.