Advertisement

Baked Ratatouille Casserole 4.2 ★

An icon representing a clock 1 h 5 min | easy | lactose-free, low-fat, Mediterranean diet, paleo-friendly, vegan
Overhead view of a baked ratatouille casserole in a white rectangular dish, with alternating upright slices of zucchini, yellow squash, eggplant, and tomato arranged in curved rows over marinara; edges are browned and sprinkled with herbs, on a whitewashed wood surface with a striped kitchen towel beside it.
Updated Nov 25, 2025
Prep Time Cook Time Total Time
25 min 40 min 1 h 5 min
Rate/Review

Introduction

This baked ratatouille casserole turns simple summer vegetables into a cozy, oven-roasted dish with deep, caramelized flavor.

Layered over a savory marinara base, every bite has tender zucchini, squash, eggplant, and tomatoes seasoned with garlic and herbs.

It makes a colorful, veggie-packed main or side dish that works just as well for weeknight dinners as for casual entertaining.

Ingredients  (4 servings)

Adjust servings:

Ingredients:

Get Ingredients →

Order the ingredients from your local store for pickup or delivery (US only). You'll check out through Instacart.
When you purchase through this link, we'll receive a small fee at no extra cost to you.

Plated baked ratatouille: a curved row of overlapping zucchini, yellow squash, eggplant, tomato, and bell pepper slices in a light marinara sauce, sprinkled with herbs, served beside a mound of white rice on a white plate.

How to Make Baked Ratatouille Casserole

  1. Prep the oven and pan

    Preheat your oven to 375°F.

    Lightly oil a 9x9 inch baking dish or similar medium casserole.

    Spread the marinara sauce over the bottom in an even layer.

  2. Slice the vegetables

    Slice the zucchini, yellow squash, eggplant, tomatoes, and red bell pepper into thin, even rounds.

    Aim for about ⅛ inch thick slices so the vegetables cook at the same rate.

    Choose a long, thin eggplant so the rounds match the zucchini size and stack more neatly.

  3. Lay out and season the vegetables

    Lay the sliced vegetables flat in a single layer on cutting boards or sheet pans.

    In a small bowl, whisk together olive oil, vegetable bouillon, garlic, thyme, oregano, salt, and pepper.

    Brush or drizzle this mixture over the vegetables, lightly coating both sides for even seasoning.

    If your bouillon is very salty, reduce the added salt or skip it.

  4. Assemble the casserole

    Arrange the seasoned vegetable slices upright in the dish, over the marinara, in snug overlapping rows or a spiral.

    Alternate zucchini, yellow squash, eggplant, tomato, and pepper so each bite has a mix of flavors.

    Pour any leftover oil mixture over the top so nothing goes to waste.

  5. Bake the ratatouille casserole

    Cover the dish loosely with foil to help the vegetables steam and soften first.

    Bake for 25 minutes, then uncover the dish so the top can lightly brown.

    Continue baking another 15 to 20 minutes, until the vegetables are very tender and edges look caramelized.

  6. Rest, garnish, and serve

    Let the casserole rest 10 minutes so the juices settle and the flavors mingle.

    Taste a slice and adjust with a pinch more salt or pepper if needed.

    Garnish with fresh basil, parsley, or extra dried herbs before serving warm.

  7. Keep it vegan and gluten-free

    Use a marinara sauce that is clearly labeled vegan and gluten-free, without cheese or wheat-based thickeners.

    Choose vegetable bouillon that is both vegan and gluten-free, or replace it with extra salt and herbs.

    Skip any dairy toppings, or use your favorite meltable vegan cheese if you like a cheesy finish.

Baked ratatouille casserole in a white rectangular dish, with thin slices of zucchini, yellow squash, eggplant, and tomatoes arranged upright in overlapping rows over marinara; the vegetables are glossy and lightly browned with herbs, with basil leaves scattered in the background.

Substitutions

Vegetable bouillon -> gluten-free vegetable bouillon or nutritional yeast
Use a vegan, gluten-free bouillon so the dish stays friendly for everyone. Nutritional yeast adds savory depth and a light cheesy note.
Eggplant -> extra zucchini and yellow squash
If you dislike eggplant, double up on zucchini and yellow squash instead. The texture stays tender, and flavors remain sweet and mild.
Fresh tomatoes -> canned fire-roasted diced tomatoes
Swap the sliced tomatoes for well-drained fire-roasted diced tomatoes tucked between the rounds. They add smoky depth and extra juiciness.

Tips

Use a mandoline for even slices
A mandoline gives perfectly even slices, which helps everything cook at the same speed and look restaurant-worthy.
Lightly salt watery vegetables if you have time
For firmer texture, lightly salt zucchini and eggplant slices, let them sit 15 minutes, then pat very dry.
Cover first, uncover to brown
Keeping the dish covered at first lets vegetables steam without drying. Removing the foil later encourages browning and deeper flavor.
Let the casserole rest before serving
Rest time thickens the juices slightly and concentrates flavor. It also makes the slices hold together better when serving.
Choose the right pan size
A smaller, deeper dish keeps slices snug and juicy. A larger pan spreads them out and gives more browning.

Nutrition Facts *

Energy 202 kcal
Protein 5 g
Total Fat 12 g
Carbohydrates 23 g
Dietary Fiber 9 g

* Approximate, per serving.
Data source: USDA FoodData Central.

FAQ

My vegetables turned out soggy and watery. What went wrong?
They may have been sliced too thick or crowded tightly without enough oven heat circulation. Next time, slice evenly, bake uncovered longer, and let the casserole rest so excess moisture absorbs.
The eggplant tastes bitter. How can I fix or prevent this?
Use younger, long, thin eggplants, which are naturally milder. You can also salt the slices, rest them, then pat dry before seasoning.
Can I prepare this casserole ahead of time?
You can assemble the dish several hours ahead, cover, and refrigerate. Add five extra minutes to the baking time when starting from cold.
Can I add protein to make it a full meal?
Stir drained chickpeas or white beans into the marinara base for extra protein. They stay tender and soak up the herby juices.
How do I reheat leftovers without drying them out?
Cover the dish and warm it at 325°F until hot, adding a spoonful of water or marinara if needed. Microwaving covered also works, but check often so the edges do not overcook.

Serving Suggestions

This baked ratatouille casserole pairs beautifully with garlicky polenta, quinoa, or a crisp green salad for contrast.

For a heartier vegan twist, spoon it over creamy mashed potatoes and finish with fresh basil, olives, or toasted pine nuts.

Leftovers taste even better the next day, so make a little extra for easy lunches.

Profile picture of Eunice

Recipe by Eunice.
“I learned to cook by standing in my grandma’s kitchen, watching her turn simple ingredients into meals that fed our entire family. That’s where it started. Today, I create recipes for real life, real kitchens, and anyone who wants good food without overthinking it.” Read more.

Main Pairings

These main dishes are a great match for this recipe.

Reviews

Rated 4.2 ★ (out of 5) based on 5 reviews.

Post your review and pictures below! ⬇︎

  • Wendy Yoshida, Houston, TX: WOW!!! 😋 Everyone kept raving about this casserole 🍅 I used jar marinara and went a little lighter on the bouillon and it was terrific 🥒 It reminded people of a really good veggie bake from a resturant. — 5 ★

    Eunice: So glad it was a hit, Wendy!

  • Liz: It was perfect. Thank you for the recipe! — 5 ★

    Eunice: So glad it turned out well, Liz!

  • Erin: Disregard the negative review, this recipe is GREAT. I made it several times and the family LOVES it. Including the picky eaters — 5 ★

    Eunice: Glad it’s been a winner for you, Erin! If you ever want it even more kid-friendly, peel the eggplant and slice everything extra thin so it bakes up super tender.

  • livingmom, Los Angeles: It wasn't that good. — 2 ★

    Eunice: Sorry it didn’t hit the mark. If it tasted flat, try a more flavorful marinara and a bit more bouillon or a pinch of salt, plus garlic and herbs (basil/thyme), and bake until the veggies are nicely tender and lightly browned.

  • Robert Roberts, Miami, FL: I love ratatouille so this casserole is definitely one I'll try. I know ahead of time that I won't use the amount of bouillon called for due to past experience of it tasting a little too salty in veggie dishes. My solution to that is to swap in a couple spoonfuls of tomato paste in the marinara and just season with a little extra garlic and herbs instead. Not only does it keep the flavor deep and savory but it lets the vegetables shine without that bouillon bite. It's a simple, easy solution. — 4 ★

    Eunice: That’s a smart swap, Robert! A little tomato paste in the marinara plus extra garlic and herbs will keep the casserole savory without the bouillon salt, and you can always taste the sauce before baking to fine-tune seasoning.

Made this recipe? How did it go?

Please post your feedback and pictures here. We’d love to hear from you!

More to Try

Browse Recipes

Dietary Pattern

Event

Season

Cuisine

Type of Dish

Course

Drinks

Equipment

Other