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This spaghetti squash casserole is my answer to a baked pasta craving on a night when I want something lighter. Roasted squash strands are tossed with a garlicky marinara, creamy ricotta, mozzarella and Parmesan, then baked until the top is bubbling and golden.
In short, spaghetti squash casserole is roasted squash strands mixed with marinara, ricotta, mozzarella and Parmesan, then baked in a 9×13 dish at 375°F (190°C) for 20 to 25 minutes. It takes about 90 minutes including roasting the squash, serves 6 and comes to about 390 calories per serving.
The first time I made it, my husband was three forkfuls in before he asked what kind of noodles I had used. That is the charm of it. You get all the cosy, cheesy comfort of a pasta bake, and the base happens to be a vegetable that holds its shape beautifully in the dish.
Quick Breakdown
Why You’ll Love This Spaghetti Squash Casserole
- It tastes like baked pasta. Marinara, ricotta and a melted cheese lid give you every flavour you expect from a pasta bake.
- It is naturally lower in carbs. The strands stand in for spaghetti, so the dish is also gluten free as long as your sauce is.
- The meat is optional. Stir in a cup of cooked ground beef or turkey, or leave it out for a vegetarian dinner.
- It is make-ahead friendly. Because the squash can be roasted days in advance, the final assembly takes minutes.
- One dish feeds six. In addition, leftover spaghetti squash casserole reheats well for lunches.
Ingredient Notes
- Spaghetti squash. 1 large one. Choose a firm, heavy squash with a deep yellow skin and no soft spots.
- Olive oil. 2 tablespoons in total; most goes on the squash and a little softens the onion.
- Seasoning. 1 teaspoon salt, 1/2 teaspoon black pepper, 1 teaspoon garlic powder and 1 teaspoon Italian seasoning.
- Onion and garlic. 1 small onion, diced, and 3 cloves of garlic, minced.
- Marinara sauce. 2 cups (480 ml). Use a thick one you like the taste of, because it carries the dish.
- Mozzarella. 1 1/2 cups, shredded. Half goes inside and half goes on top.
- Parmesan. 1/2 cup, grated, plus a little extra for the top if you like.
- Ricotta. 1 cup. It makes the filling creamy, much like the layer in a lasagne.
- Egg. 1 large, optional. It helps the filling set so it scoops out neatly.
- Cooked ground beef or turkey. 1 cup, optional. Brown and drain it first.
Swapping pasta for squash changes the numbers quite a bit. Healthline reports that a cup of spaghetti squash has 42 calories and 10 grams of carbs, against 239 calories and 47 grams for cooked pasta.
How to Cut and Roast Spaghetti Squash
To cut and roast spaghetti squash, microwave it whole for 3 to 4 minutes, halve it lengthwise and scoop out the seeds, then roast it cut side down at 400°F (200°C) for 35 to 45 minutes. The hardest part of the whole recipe is getting the knife through the squash. Here is how I make it safer.
- Soften it first. Prick the skin a few times and microwave the whole squash for 3 to 4 minutes. The knife then glides through far more easily.
- Steady it. Slice a thin piece off one side so it sits flat on the board, then cut it in half lengthwise with a large, sharp knife.
- Roast cut side down. The flesh steams against the tray and turns tender, while the edges caramelise. A sheet of parchment paper stops it sticking.
- Check with a fork. It is ready when the skin gives slightly and the flesh pulls away in strands without resistance.
How To Make Spaghetti Squash Casserole
1. Roast the squash. First, heat the oven to 400°F (200°C). Halve the squash lengthwise and scoop out the seeds. Drizzle the cut sides with olive oil, then sprinkle with salt, pepper and the garlic powder. Lay the halves cut side down on a half sheet pan and roast for 35 to 45 minutes, until tender.
2. Shred it. Next, let the halves cool for a few minutes so you can handle them. Drag a fork through the flesh from end to end and it will fall into long strands.
3. Simmer the sauce. Meanwhile, warm a little olive oil in a skillet and cook the onion until soft. Add the garlic and cook for 1 minute more. Stir in the marinara, the Italian seasoning and any salt and pepper left over from the squash, then let it bubble gently for a few minutes.
4. Mix the filling. Then put the strands in a large bowl and pour over the marinara mixture. Add the ricotta, half of the mozzarella, the Parmesan and the egg, if you are using it. Stir in the cooked meat now too, if you want it.
5. Assemble. After that, lower the oven to 375°F (190°C). Spread the mixture into a greased 9×13 baking dish. Scatter the remaining mozzarella over the top, with a final sprinkle of Parmesan.
6. Bake and rest. Finally, bake for 20 to 25 minutes, until the edges bubble and the cheese is golden. Let it rest for 10 minutes before serving, so it firms up and scoops cleanly.
How to Keep Spaghetti Squash Casserole From Getting Watery
Squash holds a lot of water, and a soupy spaghetti squash casserole is the most common complaint. Fortunately, it is easy to prevent.
- Drain the strands. Tip them into a colander for 10 minutes, or press them gently in a clean tea towel. You will be surprised how much liquid comes out.
- Do not over-roast. Mushy squash releases more water. Stop when the strands are tender but still have a little bite.
- Reduce the sauce. Those few minutes of simmering thicken the marinara, so do not skip them.
- Use the egg. It binds the ricotta and catches stray moisture.
- Let it rest. The 10 minute rest lets the juices settle back into the filling.
Tips for the Best Spaghetti Squash Casserole
- Scrape the squash lengthwise for shorter strands, or cut it into rings before roasting if you want long, spaghetti-like ones.
- Season in layers. The squash itself is mild, so the salt on the cut sides matters.
- Shred your own mozzarella if you can. It melts more smoothly than bagged.
- For a deeper golden top, slide the dish under the grill for the last 2 minutes and watch it closely.
- Grease the dish well, especially the corners, so the cheesy edges release.
Storage and Reheating
- Fridge. Cool, cover and chill leftover spaghetti squash casserole for up to 4 days. I portion leftovers into glass meal prep containers for easy lunches.
- Reheating. Cover with foil and warm at 350°F (180°C) until hot through, or microwave single portions.
- Freezer. Bake it first, cool it completely, then freeze for up to 3 months. Thaw overnight in the fridge. Expect a little extra liquid, since squash softens once frozen.
- Make ahead. Roast and shred the squash up to 3 days in advance, or assemble the whole dish in the morning and bake it at dinner time.
Variations and Substitutions
- Vegetarian. Leave out the meat and add sautéed mushrooms or a few handfuls of spinach.
- Different meat. Ground chicken, Italian sausage or even chopped pepperoni all suit the sauce.
- No ricotta? Cottage cheese works; drain it well first.
- Spicy. Add a pinch of chilli flakes to the onion.
- Prefer real pasta? Then my baked ziti with ricotta uses very similar flavours, and skillet lasagna is the quick one pan route.
The tomato sauce is pulling its weight too. Medical News Today explains that cooking tomatoes makes more of their lycopene available, so a simmered marinara is a smart base.
What to Serve With It
Because spaghetti squash casserole is rich and saucy, I keep the sides simple. A crisp green salad is all it really needs. However, when I want to stretch it for guests, I add garlic butter green beans and a basket of warm soft dinner rolls for mopping up the sauce.
Frequently Asked Questions
Ingredients and Method
Do you have to roast spaghetti squash before making a casserole?
Yes, for 35 to 45 minutes at 400°F (200°C). Raw squash will not shred, and roasting also drives off moisture and adds flavour. You can microwave it instead if you are short of time, although the strands will be wetter.
How big is a large spaghetti squash?
Look for one around 3 to 4 pounds. That gives enough strands to fill a 9×13 dish.
Can you make spaghetti squash casserole without egg?
Yes. The egg is optional and simply helps the filling hold together. Without it, the dish is a little looser but just as tasty.
Is spaghetti squash casserole gluten free?
It can be. The recipe has no flour or pasta, because the squash strands stand in for spaghetti. Still, check the labels on your marinara, cheeses and any sausage you add.
Storage and Make Ahead
Can you assemble spaghetti squash casserole the night before?
Yes, as long as you drain the strands well. Cover and chill, then add 5 to 10 minutes to the baking time because it starts cold.
Can you freeze a squash casserole like this?
Yes. Once baked and cooled, it freezes for up to 3 months; thaw it overnight in the fridge. The texture is slightly softer after thawing, so drain off any liquid before reheating.
How do you know when spaghetti squash casserole is done?
After 20 to 25 minutes at 375°F (190°C), the sauce bubbles around the edges and the cheese is melted and golden in patches. If you add the egg, the centre should reach 160°F (71°C). Rest it for 10 minutes before serving.
How long does spaghetti squash casserole last in the fridge?
Up to 4 days, covered. Refrigerate it within 2 hours of baking, then reheat under foil at 350°F (180°C) or in the microwave until it reaches 165°F (74°C).
How many calories are in a serving of this squash casserole?
About 390 calories per serving when split into 6, with roughly 23 g protein, 22 g carbohydrates and 25 g fat. These figures are estimates and change if you add the optional meat.
Ingredients
- 1 large spaghetti squash
- 2 tablespoons olive oil
- 1 teaspoon salt
- 1/2 teaspoon black pepper
- 1 teaspoon garlic powder
- 1 teaspoon Italian seasoning
- 1 small onion diced
- 3 cloves garlic minced
- 2 cups marinara sauce (480ml)
- 1 1/2 cups shredded mozzarella cheese divided
- 1/2 cup grated Parmesan cheese plus a sprinkle for the top
- 1 cup ricotta cheese
- 1 large egg optional, helps bind
- 1 cup cooked ground beef or turkey optional
Instructions
- Heat the oven to 400°F (200°C). Halve the squash lengthwise and scoop out the seeds. Drizzle with olive oil, season with salt, pepper and the garlic powder, and set cut side down on a baking sheet. Roast for 35 to 45 minutes, until tender. Cool slightly, then pull the flesh into strands with a fork.
- Soften the onion in a little olive oil in a skillet, then add the garlic and cook for 1 minute. Stir in the marinara, Italian seasoning and any remaining salt and pepper, and simmer for a few minutes.
- In a large bowl, toss the squash strands with the marinara mixture. Stir in the ricotta, half of the mozzarella, the Parmesan and the egg, if using. Add the cooked meat if you like.
- Spread the mixture in a greased 9x13 baking dish. Top with the rest of the mozzarella and a sprinkle of Parmesan. Bake at 375°F (190°C) for 20 to 25 minutes, until bubbling and golden. Rest for 10 minutes before serving.
