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Roasted Squash and Zucchini Casserole

Grill To Oven Squash and Zucchini Casserole RecipePennie can be found sharing at The Accidental Blogger, a space where she opens up about some of the things that interest her most – like travel, cooking, canning, jewelry and writing. This recipe was originally featured there.

Squash and zucchini again!?

When they’re in season, CSA boxes tend to overflow with squash and zucchini. This recipe is a really delicious way to ensure that they don’t go to waste, and it incorporates two ways of cooking that will ensure your veggies take on extra flavor and incredible texture.

Roasted Squash and Zucchini Casserole


  • 4-6 squash and/or zucchini
  • 1 large or 2 medium onions
  • 1-2 peppers (bell or red, or jalapeño if you’re going for heat)
  • 1 head garlic
  • 2-3 fresh tomatoes
  • ½ c sun-dried tomatoes in olive oil
  • ½ grated cheese (optional: when I use cheese, I use Asiago. Parmesan, and Romano would also work well. For a creamier dish, use mozzarella.)
  • olive oil
  • Seasonings (salt, pepper) and fresh or dried herbs
  • 2-3 c marinara or tomato-based sauce (You can try this no-cook sauce recipe, this crockpot meat sauce recipe, or in a pinch, buy a jar! Even easier.)


Preheat grill.

1. Prep the squash/zucchini, onions, peppers, and tomatoes:

  • Slice the squash/zucchini into ¼-inch slices, lengthwise.
  • Peel and slice onions into ¼- to ½-inch medallions.
  • Wash peppers and tomatoes.

Brush vegetables with olive oil and season (salt, pepper, or mix).

2. Place garlic head in a square of tin foil. Sprinkle with olive oil then wrap the foil securely around it.

3. Clean and lightly rub oil on the grates with oil (I douse a paper towel in oil, and, using a silicone glove or tongs, wipe the grates).

4. Place all of the vegetables on the hot grill and close. After 5 minutes, turn the vegetables. As you roast the peppers and tomatoes, handle them gently. Remember to turn the garlic as well so it roasts on more than one side.

5. As the vegetables roast take care of the following:

  • chop the sun-dried tomatoes,
  • grate the cheese (if you’re including cheese),
  • preheat the oven to 350o.

6. Remove the vegetables from the grill.

7. Prepare peppers, tomatoes, and garlic.

  • Remove the charred pepper and tomato skin.
  • Open the garlic and peel (the cloves should “pop” out of their skin).
  • Chop the roasted peppers, tomatoes, and garlic.

8. Drizzle a little marinara sauce on the bottom of a 9X13” Pyrex pan.

9. Layer:

  • squash/zucchini
  • peppers, tomatoes, garlic
  • marinara
  • cheese

Repeat until you’ve used up your vegetables. If you’re using dried herbs, this is where you layer in the oregano, thyme, and/or basil.

10. Place in the oven and cook for 20 minutes.

Add-ons and Substitutions

  • For a more substantial dish, grill chicken and add the chicken to your layers, sliced or whole.
  • In the mood for pasta, layer the vegetables with tortellini, ravioli, or other noodles.
  • Mushrooms and eggplant can be used with or instead of the squash/zucchini. Brush the mushrooms with oil and grill whole. Slice the eggplant in ½-inch slices, brush with oil, and grill. Remove skin after grilling.
  • Substitute leeks for the onions. Slice them length wise (remember to clean them out), brush with oil, and grill.
  • For zestier dishes, add lemon zest as you layer, then sprinkle with lemon juice before putting in the oven.

Copyright © 2015 by Pennie Nichols, All Rights Reserved.

Pennie Nichols

I have long been an editor, writer for hire, and textbook author. I wrote my way into a freelance career and suddenly I’m here, with socks covered in the bothersome burrs of freelancers and middle-aged women. I am not weary of writing. Every day is a new opportunity to define, invent, and discover myself through words. Words are the tools that help me dig deep into my experiences and relationships, the energy that draws me out into light and understanding. Through sharing my experiences and words, I hope to connect, to share a little light.

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Optimistic Existentialist

Thursday 30th of June 2016

I have grown to love both zucchini and squash during the past year living in Germany. This looks amazing! :)

Pennie Nichols

Friday 10th of June 2016

Truly is.

Marcia @ Menopausal Mother

Friday 10th of June 2016

This looks totally yummy!

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