Sunday Baked Vegetable Casserole

Name: Sunday Baked Vegetable Casserole
Prep time: 20 min
Cook time: 45 min
Total time: 1 h 5 min
Yield: 6 servings
Ingredients: 2 cups chopped zucchini; 2 cups chopped bell peppers (any color); 1 cup chopped spinach; 1 cup chopped mushrooms; 1 cup diced tomatoes (canned or fresh); 1 small onion, diced; 2 cloves garlic, minced; 2 cups cooked quinoa or rice; 1 cup shredded mozzarella cheese; 1/2 cup grated Parmesan cheese; 1 teaspoon dried oregano; 1 teaspoon dried basil; Salt and pepper to taste

Highlighted under: Baking Moments

I love making this Sunday Baked Vegetable Casserole as it fills the kitchen with incredible aromas and brings everyone together. With layers of colorful vegetables sprinkled with herbs and cheese, it’s a delightful way to enjoy a wholesome meal. Not only is it packed with nutrients, but it also makes for perfect leftovers. Whether you’re feeding a crowd or just looking for a hearty meal to enjoy throughout the week, this casserole never disappoints!

Created by

Adeline Morris

Last updated on 2026-01-13T23:31:11.048Z

When I first tried this casserole, I was amazed at how simple it was to prepare yet how flavorful it turned out. I found that roasting the vegetables beforehand intensified their natural sweetness, making every bite a taste sensation. I love to mix seasonal veggies, but the combination of bell peppers, zucchini, and spinach works particularly well!

Another tip is to let the casserole rest for a few minutes after taking it out of the oven. This allows the layers to set, making it much easier to serve. My family can't get enough of this dish, and it’s a great way to use up any leftover vegetables in the fridge.

Why You'll Love This Recipe
Bursting with seasonal flavors and vibrant colors
Comfort food that's also packed with nutrients
Easily customizable with your favorite veggies and spices

Choosing the Right Vegetables

The beauty of this Sunday Baked Vegetable Casserole lies in the choice of vegetables. While this recipe calls for zucchini, bell peppers, and mushrooms, feel free to experiment with seasonal produce. Root vegetables like carrots or parsnips can add sweetness and earthiness, while leafy greens such as kale or Swiss chard can enhance the nutritional profile. Just remember to chop them uniformly to ensure even cooking and ensure they soften perfectly during the baking process.

When selecting your vegetables, prioritize freshness. Vibrant, firm vegetables will not only taste better but will also contribute to a visually appealing casserole. Keep in mind that denser vegetables may require a longer sautéing time to soften adequately, so adjusting timing accordingly is key. Aim for a colorful combination that excites the palate and increases the meal's overall nutrient density.

Enhancing Flavor Profiles

The addition of herbs in this casserole, like oregano and basil, elevates the dish immensely. Fresh herbs can substitute dried ones for a more vibrant flavor; however, make sure to adjust the quantities since fresh herbs are generally more potent. To enhance the taste further, consider incorporating a dash of red pepper flakes for a bit of heat or a splash of balsamic vinegar for acidity, which can cut through the richness of the cheese beautifully.

For those avoiding dairy, you can replace cheese with a plant-based alternative, which can still yield a creamy texture when melted. Nutritional yeast is another great addition, lending a cheesy flavor without actual cheese. Regardless of the choices, tasting the mixture before baking allows you to fine-tune the seasoning and savor the medley of flavors before it transforms in the oven.

Ingredients

Gather the following ingredients to make your casserole:

Vegetable Ingredients

2 cups chopped zucchini
2 cups chopped bell peppers (any color)
1 cup chopped spinach
1 cup chopped mushrooms
1 cup diced tomatoes (canned or fresh)
1 small onion, diced
2 cloves garlic, minced

Casserole Base

2 cups cooked quinoa or rice
1 cup shredded mozzarella cheese
1/2 cup grated Parmesan cheese
1 teaspoon dried oregano
1 teaspoon dried basil
Salt and pepper to taste

Instructions

Follow these steps to prepare your delicious casserole:

Preheat the Oven

Preheat your oven to 375°F (190°C).

Sauté the Vegetables

In a large skillet, heat a tablespoon of olive oil over medium heat. Add the onion and garlic; sauté until translucent. Gradually add the zucchini, bell peppers, and mushrooms, cooking until they soften, about 5 minutes.

Combine Ingredients

In a large bowl, combine the sautéed vegetables with cooked quinoa or rice, chopped spinach, canned tomatoes, oregano, basil, salt, and pepper. Mix until well combined.

Assemble the Casserole

Transfer the mixture to a greased baking dish, spreading it evenly. Top with mozzarella and Parmesan cheese.

Bake

Cover with aluminum foil and bake for 30 minutes. Remove the foil and bake for an additional 15 minutes, or until the cheese is bubbly and golden.

Serve

Let the casserole rest for 10 minutes before slicing and serving. Enjoy your delicious Sunday Baked Vegetable Casserole!

Pro Tips

Feel free to use any vegetables you have on hand. Swap in broccoli, carrots, or even sweet potatoes for a different twist. This dish also freezes well, so consider making a double batch for later use.

Make-Ahead and Storage Tips

This casserole is an excellent make-ahead option. Prepare it the day before, cover it tightly with foil, and refrigerate. This extra time allows the flavors to meld together beautifully. On the day you plan to serve, simply pop it in the oven from the fridge, adding an extra 10-15 minutes to the baking time to ensure it is heated through. For longer storage, it freezes well—just slice into individual portions and wrap tightly before freezing.

When storing leftovers, allow the casserole to cool completely, then transfer it to an airtight container. It should keep in the refrigerator for up to four days. Reheat in the oven at 350°F (175°C) until warmed through or in the microwave for a quick meal. Ensure to cover with a damp paper towel if using the microwave to keep the moisture intact and prevent drying out.

Serving Suggestions

This casserole is versatile when it comes to serving options. It pairs wonderfully with a crisp side salad or crusty bread to soak up the juices. For a heartier meal, consider serving it alongside grilled chicken or fish for additional protein. Alternatively, topping it with a poached egg can transform it into a nourishing brunch dish.

Feel free to get creative with garnishes, such as fresh herbs or a sprinkle of additional cheese before serving for a touch of elegance. Drizzling it with a bit of high-quality olive oil can also add a luxurious finish. The goal is to make each serving not just a meal but an experience that highlights the beautiful flavors of the vegetables and the delightful textures of the cheeses.

Questions About Recipes

→ Can I make this casserole ahead of time?

Absolutely! You can prepare the casserole a day in advance and store it in the refrigerator. Just bake it right before serving.

→ What if I want a vegan version?

To make it vegan, simply omit the cheese and replace it with a plant-based alternative or skip it altogether.

→ How can I add protein to this dish?

You can easily add cooked beans, lentils, or even shredded chicken to the mix for extra protein.

→ What sides pair well with this casserole?

A simple green salad or garlic bread are great choices to accompany this comforting dish.