Cheesy Spaghetti Squash Casserole Recipe

Preheat the oven to 425 degrees F. Line a baking sheet with parchment. Brush or spray a shallow 2-quart baking dish with oil.

Cut the squash in half lengthwise and scrape out the seeds. Sprinkle with ¼ teaspoon salt and ⅛ teaspoon pepper. Place on the baking sheet with the cut sides down.

Bake for 30 to 40 minutes, or until the squash is tender when pierced with the tip of a paring knife. Remove from the oven and turn the squash so the cut sides are facing up.

Return the squash to the oven and bake for another 5 minutes to dry out any excess liquid. (The squash won’t necessarily look dry.) Remove and let cool.

In a large skillet set over medium heat, add 1 tablespoon of oil. Once the oil begins to shimmer, add the onions, ¼ teaspoon salt, and ¼ teaspoon pepper.

Cook, stirring occasionally, for 5 minutes or until softened. Stir in the garlic, red pepper slices, and sage. Cook and stir for another 1 minute. Transfer to a large bowl.

In a blender (immersion or countertop), pulse the eggs, milk, flour, ½ teaspoon salt, and ⅛ teaspoon pepper 3 to 4 times, or until the mixture is smooth.

With a fork, flake the squash strands into the bowl on top of the onions. Add 1 teaspoon salt and mix until combined.

Add the egg mixture, grated Jarlsberg cheese, and ¼ cup of the Parmesan to the squash. Stir to combine.

Bake the casserole: Transfer the squash mixture to the baking dish and sprinkle it with the remaining ¼ cup Parmesan. Bake for 40 to 45 minutes.

Let rest for 10 to 15 minutes before serving as a side dish or a vegetarian main.