Spaghetti Squash Casserole (Lasagna Style)

So here’s how this ended up in my oven

I made this Spaghetti Squash Casserole the first time after my neighbor handed me a gigantic squash like a baton at a relay. I blinked, laughed, and said sure, why not, let’s make it lasagna style. The kitchen smelled like Sunday dinner, but it ate more like Tuesday night, comfy and easy. And yes, I did play the same three songs while it baked because I am a creature of habit. This casserole is cozy, a little lighter, and honestly, its cheesy personality wins people over fast.

Also, brief detour. I once tried to teach my dog to sit while the squash cooled. She learned sit, I learned patience. Win win, sort of.

Why you’ll love this, or at least why I do

• I make this when I want lasagna vibes without the whole noodle situation. It still feels special.
• My family goes a bit bonkers for the browned mozzarella top, even the picky one who claims to not like squash. Okay buddy.
• It reheats like a dream. Actually, I find it works better if it rests a while, but I am not always that patient.
• When I’m wiped, I use store sauce, and nobody complains. When I’m feeling extra, I simmer my own and feel very fancy, for like ten minutes.
• I used to end up with a watery casserole and it bugged me, but I figured out a couple tricks, and boom, problem solved.

Here’s what you’ll need

• 1 large spaghetti squash, about 1.2 to 1.5 kg
• 2 tablespoons olive oil
• 1 small onion, diced
• 3 cloves garlic, minced
• 450 g ground turkey or beef, or skip for vegetarian
• 2 cups marinara sauce (I grab Rao’s when I am in a hurry, but any decent jar works fine)
• 1 teaspoon Italian seasoning, plus a pinch of red pepper flakes
• 1 cup ricotta cheese (cottage cheese works in a pinch, and my grandmother always insisted on a particular brand, but honestly any version is fine)
• 1 large egg
• 1 cup shredded mozzarella, plus a handful extra for the top
• 1/2 cup grated Parmesan
• 1 big handful baby spinach, roughly chopped, optional
• Fresh basil, torn, for serving
• Kosher salt and black pepper

Optional swaps I use sometimes

• Greek yogurt mixed with ricotta for extra tang
• Mushrooms instead of meat, just cook them down well
• Smoked mozzarella for a wee bit of campfire flavor

How to make it, with a few real life asides

1. Heat the oven to 400 F. Carefully halve the spaghetti squash lengthwise and scoop out the seeds. Rub the cut sides with 1 tablespoon olive oil, season with salt and pepper, and place cut side down on a lined baking sheet. Roast 35 to 45 minutes until the skin gives when pressed and the strands pull easily with a fork. Do not rush this. I once tried, regretted it, and the squash fought back.
2. Scrape the squash into a bowl and let it cool a bit. Now the important part. Pile the strands into a clean towel or a few paper towels and squeeze out excess moisture. If you skip this, you get squash soup. Ask me how I know. Season lightly with salt and pepper. This is where I sneak a taste.
3. While the squash roasts, warm a skillet with the remaining 1 tablespoon olive oil. Add the onion and cook until translucent, 4 to 5 minutes. Stir in the garlic for 30 seconds. Add ground meat if using, cook until browned, then drain if needed. Stir in marinara, Italian seasoning, and red pepper flakes. Simmer on low 5 minutes, just to say hello to each other.
4. In a bowl, mix ricotta, egg, Parmesan, a pinch of salt and pepper. On second thought, add a squeeze of lemon if you like it bright. I tend to think it wakes things up.
5. Lower oven to 375 F. Lightly oil a 9 by 13 inch baking dish. Layer like lasagna. Start with a thin smear of sauce. Add half the squash, half the ricotta mixture in spoonfuls, a sprinkle of mozzarella, then half the sauce. Scatter the spinach if using. Repeat layers and finish with extra mozzarella on top. If it looks a bit messy, good, it is supposed to.
6. Bake 20 to 25 minutes until bubbling around the edges and the top is golden in spots. If you like it extra bronzed, slide it under the broiler for 1 to 2 minutes, but do not walk away, please. Learned that the hard way.
7. Rest 10 minutes before slicing. It sets up as it cools, which is magic, and also science. Finish with torn basil.

By the way, if you want a deep dive on roasting technique, I like the walkthrough at The Kitchn, and this helpful guide to spaghetti squash basics on Serious Eats. Curious about ricotta texture and quality? The overview at Bon Appetit is a nice read.

Notes from lots of tries

• Salting and squeezing the squash matters. The one time I skipped it, we needed spoons.
• An egg in the ricotta helps it hold together. Without it, still tasty, just softer slices.
• Use a flavorful sauce. Mild sauce makes a mild casserole. Add a pinch of sugar if your sauce tastes too sharp.
• If you accidentally over salt the sauce, fold in a spoon of ricotta to mellow it out.
• Let it rest. Ten minutes minimum. Fifteen if you can stand it.

Variations I’ve tried

• Vegetarian mushroom and spinach. Brown the mushrooms hard so they do not steam. Delicious.
• Sausage and kale. A little fennel seed, oh yes.
• White pesto version. Skip the red sauce, use a light pesto cream with ricotta. Lovely but rich. Small portions.
• Dairy light. Use part skim mozzarella and cottage cheese. Still cozy.
• One that did not work. I added chopped raw zucchini once. Too wet, kind of bland. I would cook it down first next time.

Gear I use, plus a workaround

• A sharp chef knife. Feels essential for the squash. Actually, if yours is dull, poke the squash a few times with a fork and microwave it 3 to 5 minutes to soften before cutting.
• Rimmed baking sheet lined with parchment for easy cleanup.
• Large skillet for the sauce.
• Mixing bowls and a sturdy spoon. Any will do. I used a wooden spoon inherited form my aunt, which makes me smile every time.
• Box grater. Pre shredded is fine though, no judgement.

How to store it

Cool completely, then cover and refrigerate up to 4 days. I think it tastes even better the next day. Freeze slices tightly wrapped up to 3 months. Reheat in a 350 F oven until hot, about 15 to 20 minutes, or microwave in short bursts. Though honestly, in my house it never lasts more than a day.

What to serve it with

I love this with a big green salad and a garlicky vinaigrette, plus a hunk of bread if you are feeling jaunty. A little chili flake on top for me, and my partner likes a drizzle of balsamic. Friday night tradition is this casserole with a glass of red and the good playlist. Yall can do sparkling water with lemon and feel just as fancy.

Pro tips, learned the slightly annoying way

• I once skipped squeezing the squash because I was late. The casserole flooded. Never again.
• Over saucing is tempting, but it can go watery. Keep layers modest, you can spoon extra sauce at the table.
• Let the casserole rest. If you cut too soon, slices slump and nobody gets those tidy squares.
• Taste your sauce before layering. Fix it there, not later. A pinch of salt or a splash of vinegar can save the day.

FAQ I keep getting

Can I make it vegetarian? Absolutely. Skip the meat, add mushrooms or lentils, and you are good.

Do I need the egg? No, but it helps the ricotta layer set. Without it, the texture is softer and a bit more rustic.

Is this low carb? Lower than pasta lasagna, yes. Not carb free, but friendly if you are watching that sort of thing.

Can I use cottage cheese? Yup. Blitz it in a blender for a few seconds if you want it smoother, or leave it chunky, both work.

Why is mine watery? Usually it is under roasted or not squeezed. Roast until strands pull easily, then squeeze. Also go lighter on sauce.

Can I prep ahead? Yes. Assemble, cover, and refrigerate up to 24 hours. Bake straight from the fridge, adding a few extra minutes.

Do I have to peel the squash? No. Roast it in halves and scoop the strands. Peeling would be a proper nuisance.

Microwave the squash instead of roasting? You can. Halve, place cut side down with a splash of water, and microwave until tender. Roasting has better flavor, but weeknights are weeknights.

What size pan? A 9 by 13 works great. Two smaller dishes also work if you want one for later.