Healthy Spaghetti Squash Au Gratin

Healthy Spaghetti Squash Au Gratin is for anyone craving classic comfort food with a healthy twist. Tender spaghetti squash soaks up all the creamy flavor of Greek yogurt and sharp cheddar cheese for a dish that is cozy but light enough for any night of the week. Every forkful brings that melted cheese satisfaction while sneaking in a veggie boost that even picky eaters never suspect.

I first made this after we went overboard at the farmers market and ended up with three spaghetti squashes on the counter. Now my husband requests it for every holiday dinner.

Ingredients

• Spaghetti squash: gives a perfect noodle-like texture without gluten. Look for one that feels heavy and has firm skin for best results
• Olive oil: adds subtle richness and helps roast the squash perfectly. Choose a good extra virgin oil for flavor
• Onion: infuses savory sweetness into every bite. Go for yellow or sweet onions to keep the flavors balanced
• Garlic: provides that fragrant backbone to the dish. Use fresh cloves for the best flavor
• Plain Greek yogurt: keeps things creamy and light while adding protein. Use full-fat for extra richness
• Sharp cheddar cheese: brings that iconic melty tang. Picking extra sharp cheddar delivers more flavor with less cheese
• Salt: ties all the flavors together. Opt for kosher or sea salt if possible
• Black pepper: adds warmth and depth. Freshly cracked offers the best bite

Step-by-Step Instructions

Prepare the Squash:

Slice the spaghetti squash in half lengthwise and scoop out the seeds with a sturdy spoon. Brush the inside with olive oil. Place the squash cut side down on a baking sheet lined with parchment if you want easy clean up. Roast at a steady 400 degrees until the flesh is tender and pulls away in long strands when you run a fork through it. This usually takes around 35 to 40 minutes. Take your time here as a tender squash is the foundation of a great gratin

Sauté Aromatics:

While your squash is roasting prepare the base. Dice the onion into small pieces so they melt into the mixture later. Heat olive oil in a skillet on medium and let the onion cook slowly until translucent and fragrant. Toss in the minced garlic and stir until your kitchen smells amazing about one minute longer

Shred the Squash:

When the squash is cool enough to handle flip each half over. Hold with an oven mitt and scrape lengthwise with a fork. The strands should come out easily. Place them into a large bowl for building your gratin

Mix Filling:

Add the cooked onions and garlic to the squash. Dollop in the Greek yogurt and most of the shredded cheese saving some for topping. Season with salt and pepper. Use a big spoon to combine everything until you have a creamy tangle of squash coated in sauce

Assemble and Bake:

Grease a casserole dish to prevent sticking. Spread the squash mixture into an even layer patting it down gently. Top with the reserved cheddar. Bake at 375 degrees until the casserole is golden brown and bubbling at the edges about 20 to 25 minutes. Broil for a minute or two if you love an extra cheesy crust

Save

My favorite part of this recipe is always that crispy cheese top layer. When my sister comes to visit we actually fight over who gets the gooey corners as they always turn out the most golden and delicious.

Storage Tips

Let leftovers cool completely before storing. I use an airtight glass container in the fridge and this keeps well for up to four days. You can also freeze individual portions and reheat in the oven for busy lunches

Ingredient Substitutions

Swap Greek yogurt for cottage cheese or sour cream if you want a different tang. If you like a bolder flavor try smoked gouda or gruyère instead of cheddar. To sneak in more greens add a few handfuls of chopped spinach before baking

Serving Suggestions

This gratin makes a satisfying vegetarian main with a crisp green salad or pairs beautifully as a side with roast chicken or grilled fish. It is especially delicious on a brunch table with eggs and a sliced tomato salad

Cultural Context

Traditional au gratin dishes come from French cuisine and usually use potatoes and rich cream. By swapping in spaghetti squash and Greek yogurt you get that classic comfort but with a lighter and fresher twist that fits modern eating goals

Recipe FAQs

→ What makes this dish creamy without heavy cream?

Greek yogurt adds rich creaminess while keeping the dish lighter and boosting protein content.

→ Can I make this dish ahead of time?

Yes, assemble and refrigerate before baking. When ready to serve, bake until heated through and golden.

→ Is spaghetti squash a good pasta alternative?

Spaghetti squash offers a noodle-like texture with fewer carbs, making it a popular pasta swap.

→ What kind of cheese works best?

Sharp cheddar gives bold flavor, but gruyere or part-skim mozzarella are also good options for melting.

→ How do I get the squash strands just right?

Roast until tender, then use a fork to create long, spaghetti-like strands for ideal texture.