Sheet Pan Italian-Style Spaghetti Squash

Halve the squash crosswise. Scoop out the seeds and discard. Brush the cut sides of the squash with 2 teaspoons oil, then season with 1 teaspoon salt and several grinds black pepper. Arrange the squash cut side down on a large baking sheet. Roast until the squash flakes easily with a fork but is still al dente, 25 to 30 minutes. Remove from the oven and flip the squash upright to cool. Leave the oven on. 

Meanwhile, heat 1 tablespoon oil in a large, deep skillet set over medium-high heat until shimmering. Add the mushrooms and cook, stirring, until the liquid has evaporated and the mushrooms are starting to turn golden brown, about 5 minutes. Add the onions and 1/2 teaspoon salt and cook, stirring, until the onions have softened, about 4 minutes. Transfer to a large plate. 

Return the skillet to medium heat and add the remaining 1 tablespoon oil. Crumble in the tempeh and cook, breaking it into smaller pieces with a wooden spatula, until golden brown, 3 to 4 minutes. The skillet may be dry and that’s okay! Add the garlic, oregano, red pepper flakes, remaining 1/2 teaspoon salt, and several grinds black pepper and cook for 1 minute.

Add a splash of the marinara sauce and scrape up any brown bits from the bottom of the skillet. Stir in the remaining marinara, followed by the mushrooms and onions. Simmer for 5 minutes to allow the flavors to meld. Season with salt to taste. 

When the squash is cool enough to handle, scrape the strands onto the baking sheet. Add most of the sauce, the basil, and half the mozzarella and toss to coat. Spread into a single layer. Dollop the cottage cheese evenly over top. 

Add the remaining sauce in spoonfuls and top with the remaining mozzarella and all of the Parmesan. Return to the oven (still at 450°F) and bake until the sauce is bubbly and the top is lightly browned, 10 to 15 minutes. Garnish with fresh basil.

Let cool for 5 minutes before slicing into 6 large rectangles. Serve with crusty bread, if desired.