Recipe

Creative Squash Casserole

A healthy, wholesome squash casserole with a bright lemony yogurt sauce, tender roasted squash, and a crispy whole grain topping that stays crunchier than most.

By Matt Campbell

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4.8

A golden baked squash casserole in a white ceramic baking dish with a crispy oat and pecan topping, fresh herbs sprinkled on top, sitting on a wooden table with a serving spoon

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This is the squash casserole I make when I want comfort food energy but I also want to feel like I ate a vegetable on purpose. It is cozy and spoonable in the middle, crisp on top, and it has a little pop from lemon and Dijon that keeps the whole thing from tasting like a beige side dish.

The “creative” part is the move that changes everything: we roast the squash first. That drives off water, concentrates flavor, and keeps the casserole from going soft and soupy. Then we fold it into a light, creamy sauce built from Greek yogurt and a bit of Parmesan, and finish with a crunchy topping that is half pantry, half magic.

Sliced yellow squash and zucchini roasting on a parchment lined sheet pan with olive oil and herbs

Why It Works

No watery casserole: Roasting the squash first evaporates moisture so the filling stays creamy, not puddly.
Big flavor without heavy ingredients: Greek yogurt plus Parmesan gives tang and richness while keeping it lighter than a traditional mayo or condensed soup base.
Crisp top, tender center: A toasted oat and whole wheat breadcrumb topping bakes up crunchy and stays crunchier than most.
Weeknight friendly: Everything is straightforward, and you can prep components ahead so dinner feels suspiciously easy.

Pairs Well With

Storage Tips

Refrigerate

Let the casserole cool, then cover tightly or transfer to an airtight container. Refrigerate for up to 4 days (for best quality).

Reheat

Oven (best for a crisp top): For individual portions, bake at 350°F for 15 to 20 minutes, uncovered. For a larger amount or most of the pan, plan on 25 to 35 minutes. If the top is browning before the center is hot, cover loosely with foil for the first half, then uncover to re crisp.
Microwave (fast): Heat individual portions in 45 to 60 second bursts. If the topping softens, finish under the broiler for 1 to 2 minutes.

Freeze

You can freeze it, but the yogurt sauce may loosen a bit when thawed. If you plan to freeze, freeze without the topping for best texture. Wrap well and freeze up to 2 months (for best quality). Thaw overnight in the fridge, add fresh topping, then bake until hot.

Common Questions

Can I use only yellow squash or only zucchini?

Yes. Use whatever you have. If you use all zucchini, roasting is even more important since zucchini holds a lot of water.

How do I keep squash casserole from getting watery?

Roast the squash on a hot sheet pan in a single layer until you see browned edges and some steam has cooked off. If your pan is crowded, use two pans so the squash roasts instead of steams. Also, let the squash cool for a few minutes before mixing so it does not dump extra liquid into the sauce.

Can I make this gluten free?

Yes. Swap the whole wheat breadcrumbs for gluten free breadcrumbs, and use certified gluten free oats.

Can I make it dairy free?

You can, but the flavor will change. Use a thick, unsweetened dairy free yogurt, a dairy free Parmesan style alternative, and olive oil instead of butter in the topping.

What protein can I add to make it a full meal?

Stir in 1 1/2 cups shredded rotisserie chicken, or fold in 1 (15-ounce) can of rinsed white beans after roasting the squash. Both work great with the lemony sauce.

Matt Campbell

I have always had a huge passion for the culinary arts, people, working as a team, and so on. I wanted to pursue my love for cooking initially at Virginia Commonwealth University with a culinary arts degree; however, I instead decided to apply myself and acquire more practical skills. My end goal is to eventually open my own restaurant or similar establishment.

Kitchen Essentials

9x13-inch baking dish (about 3-quart)
Rimmed sheet pan (use 2 if needed)
Parchment paper (optional, for easier cleanup)
Large mixing bowl
Skillet (for softening onion and toasting topping)
Box grater or microplane (for garlic and Parmesan)
Measuring cups and spoons

I started making versions of this when I realized summer squash shows up in bags, boxes, and neighbor drop offs like it has a key to your house. My first few casseroles were fine but a little too soft, a little too polite. Then I tried roasting the squash first, and suddenly it tasted like something you would actually fight over at the table. Now it is my go to when I want a wholesome side that still has crisp edges, real seasoning, and that “wait, what is in this?” reaction.