Stuffed Spaghetti Squash

Squash halves roasted until the strands pull free with a fork, then loaded back into their own shells with a mushroom-heavy beef sauce and baked again under mozzarella. The shell does the work a casserole dish would, and half the squash stays behind as the base.

Ingredients

For the squash

• 1 spaghetti squash, about 4 lb / 2 kg
• 1 tbsp olive oil
• Salt and pepper

For the sauce

• 1 tbsp olive oil
• 1 large white onion, finely diced
• 1 lb / 454 g lean ground beef
• 4 cloves garlic, minced
• 200 g cremini mushrooms (8–9), sliced
• 1 cup tomato passata or tomato sauce
• 1 tsp salt
• ½ tsp freshly ground black pepper
• ¼ cup finely chopped fresh basil

Toppings

• 1 cup mozzarella, grated
• ¼ cup grated Parmesan
• Fresh parsley, finely chopped — optional

Instructions

1. Heat the oven to 425°F. Cut the squash in half lengthwise and scrape out the seeds. Set the halves cut side up on a foil- or parchment-lined baking sheet, drizzle with olive oil, and season with salt and pepper. Bake 45–50 minutes, until the strands pull easily from the shell with a fork.
2. Meanwhile, heat 1 tbsp olive oil in a large skillet over medium. Cook the onion 5 minutes, until it turns glassy. Add the beef and cook another 5 minutes, breaking it up as it browns. Add the mushrooms and garlic and keep going until no pink is left and the mushrooms have softened.
3. Pour in the passata, bring to a boil, then lower the heat, cover, and simmer 15 minutes. Off the heat, stir in the fresh basil.
4. Pull the squash from the oven. When it's cool enough to handle, scrape about half the strands out of each shell and stir them into the sauce. Scoop the mixture back into the shells, top with mozzarella, then the Parmesan.
5. Return to the oven for 10–15 minutes, until the cheese is melted and bubbling. Sprinkle with parsley.

Make-Ahead & Storage

Covered in the fridge, the filled halves keep 3 days. The sauce on its own freezes up to 6 months, so a double batch buys a second dinner that only needs a squash roasted.

Roast the squash a day ahead if that's the part that doesn't fit the evening — it reheats inside the second bake without going soft.

Notes

Scrape only about half the squash out of each shell. Take more and the sauce has nothing to sit on; the remaining strands hold the shape and soak up the tomato while it bakes.

Passata gives a cleaner tomato flavor than canned sauce, but either works. If the sauce looks thin after simmering, uncover it for the last few minutes — a wet sauce turns the shell soupy.

The mushrooms are doing real work here, not filling space: they carry the beef further and keep a single pound feeding six.