Roasted Squash and Zucchini with Mustard Sauce

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Roasted Zucchini and Squash are covered in a creamy mustard sauce, topped with cheddar cheese and baked until gooey and delicious. This easy side dish is ready in under 45 minutes!

This recipe was originally published in January 2017. It has been updated for content and photos.

When the squash and zucchini are in season, it's the perfect time to roast them. Because there is just SO MUCH. You've got to come up with new ways to cook it.

This Roasted Squash and Zucchini has such a great flavor with the mustard sauce and cheddar cheese. So simple, but so delicious. This has become a favorite way of eating squash in my house.

Next time you need an easy side dish, the zucchini and squash casserole is the way to go!

Why This Recipe Works

1. The squash and zucchini are sliced thin so they cook through fully;
2. The cheese is added at the end to ensure it doesn't burn while the squash roasts;
3. It's super easy and a great way to get everyone to eat their veggies!

Step By Step Instructions

Preheat oven to 375F degrees.  Slice zucchini and summer squash horizontally into thin strips (about ¼" thick). I find using a mandolin to be helpful for this step.

Lightly salt and place in a colander for 10 minutes to draw out excess moisture. Dry with paper towels.

Drizzle about 1 teaspoon of olive oil in the bottom of a baking dish.  Place one layer of squash in the bottom of the pan.

Spread a thin layer of Dijon mustard on top of the squash.  Put another payer of squash, in a crisscross pattern.  Cover with a thin layer of Dijon mustard. Continue until all squash has been layered and mustard used up.  Drizzle olive oil on the top and place in oven.

Bake for 20 minutes.  Remove from oven and sprinkle with cheese.

Bake for another 10-15 minutes, or until cheese is bubbling and starting to brown. If the cheese has not browned, you can stick it under the broiler for a few minutes - just make sure you don't burn it.

Expert Tips

1. Lightly salt the zucchini and squash and let it sit in a colander 10 minutes before cooking. This helps draw out excess water so the zucchini and squash casserole doesn't come out watery.
2. If the cheese isn't brown enough, place it under the broiler for a couple minutes to let it get browned and bubbly. Watch it to make sure it doesn't burn.
3. For best results, use a mandolin to slice the zucchini and squash into ¼" slices.

Frequently Asked Questions

1. How do you make zucchini not soggy? You can salt it and let it sit 10 minutes before adding it to the baking dish to draw out some of the moisture.
2. Do you peel yellow squash? You do not need to peel the yellow squash or zucchini in this recipe.
3. Should I remove zucchini seeds? You do not need to remove the zucchini seeds. The whole thing is edible! However, if you happen to have a zucchini with very large seeds, you can remove them if desired.
4. Is yellow squash similar to zucchini? Both are from the squash family and have a relatively mild flavor. Yellow squash tends to have more seeds, but they are still edible. They can be substituted for each other in recipes.
5. Should you salt zucchini before cooking? You can lightly salt zucchini and place it in a colander for about 10 minutes to draw out the moisture. This will help prevent it from becoming soggy. Dry it then cook it.

Make it a Meal

• Start your meal with this delicious Strawberry Spinach Salad (it's sooooo good!);
• Serve the roasted zucchini and squash with the Crawfish Pie, these easy Grilled Cornish Game Hens or these Grilled Lamb Chops;
• They also go well with these Easy Scalloped Potatoes, these Sauteed Mushrooms or these Crispy Roasted Potatoes.
• Don't forget dessert....serve this Lemon Chiffon Pie, this Fruit Galette, or these Mini Pavlovas (with berries and lemon curd).

More Squash Favorites

• Easy Grilled Squash;
• Oven Fried Squash;
• Calabacitas;
• Butternut Squash Soup;

You May Also Like These Other Roasted Vegetable Recipes

• Parmesan Roasted Asparagus;
• Grilled Fruit Kebabs (not exactly a vegetable, but you get the gist);
• Curry Roasted Winter Vegetables;
• Korean Cauliflower Wings;
• Browse ALL the Vegetable Recipes!!

Did you make this roasted zucchini and squash recipe? Rate the recipe and leave a comment to let me know how it turned out 🙂