Baked Mexican Quinoa Casserole

If you’re looking for a crowd-pleasing casserole that is perfect for hosting or for having lots of leftovers, this is the recipe for you. This Mexican quinoa casserole is the tastiest vegetarian-friendly dish that can be made in just 30 minutes.

With tons of veggies hidden inside, even the pickiest of eaters are going to love this quinoa casserole. Mexican-style dishes can often be on the heavier and more indulgent side, and while there’s no shortage of cheese on this casserole, it is still packed with healthy veggies. 

What You'll Learn In This Recipe

• How to make a simple dinner everyone will love!
• The basic method for cooking tasty quinoa. 
• A simple switch to make this recipe vegan-friendly.

If you love this baked quinoa casserole recipe and want to learn more ways to expand your skills in the kitchen, check out my free guide to instantly become a better chef. 

Ingredients You Need

This baked quinoa dish calls for ingredients that all join together to make the most delicious Mexican casserole. 

Dried quinoa: This is the structure for your casserole so be sure to pick your favorite brand of quinoa. Optionally, you can use a red or multi-colored quinoa.

Water: You will need the water for cooking the quinoa. 

Extra-virgin olive oil: This is my oil of choice for sautéeing up vegetables.

Bell pepper: Red, orange, or yellow bell peppers are all perfect for this dish. I prefer using one red and one orange pepper. 

Green bell peppers are much less sweet and can result in an overpowering bitter-pepper flavor. 

Red onion: Need help dicing an onion? Check out this one-minute tutorial! You'll be chopping onions like a chef in no time!

Garlic: ½ teaspoon of garlic powder could be used to replace the fresh or jarred minced garlic.

Canned black beans: Be sure to drain and rinse before using. Draining will prevent the beans from making the casserole watery and rinsing them off will remove any excess salt and build up on the beans.

Canned diced tomatoes with green chilies: This is the easiest way to get a huge boost of flavor without having to do a bunch of prep work. You can also substitute for a regular can of diced tomatoes if needed.

Tomatillo salsa: This will add a nice bit of acidity and spice to the casserole. Feel free to substitute for another type of salsa to change the flavor, make the dish more spicy, or accommodate what you have on hand.

White cheddar cheese: This can be substituted for any type of cheddar cheese or Colby Jack. Optionally, you can remove the cheese together to turn this into a lighter-tasting and vegan version of the dish.

Avocado: This is an entirely optional garnish. I personally can’t live without avocado on top!

Green onions: When using green onions to garnish, I always recommend cutting on the bias for a beautiful texture and look.

How To Make This Recipe

This quinoa casserole is a Mexican style dish that will shock you with how easy it is to make. 

1. To begin, grab a medium-sized saucepan and add the quinoa and water. Cook the quinoa as instructed on the package. 

Cooking quinoa is very similar to cooking rice. Add the quinoa and water to the pot to begin, then bring the water up to a boil. Once boiling, immediately drop the heat to a simmer, add the lid, and let the quinoa cook until no water remains.

2. As the quinoa cooks, heat the olive oil in a 12-inch cast iron skillet over medium-high heat. Once the oil is hot, add the bell peppers and onion. 

Cook for about 7 minutes, stirring occasionally. When the onions are translucent, that is your sign that the vegetables are finished. 

Be very careful not to cook the vegetables at too high of heat otherwise, they will burn. Cooking at medium-high or even medium heat while stirring will still break down and soften the vegetables without having to crank anything up too high. 

3. Reduce the heat on the cast iron skillet to low and add the garlic, black beans, and tomatoes with chilies. Let this cook for an additional two minutes. When the 2 minutes are up, remove the pan from the heat. 

4. While you are cooking the vegetables, be sure to pay attention to the quinoa as needed. When the quinoa is finished cooking, mix with the salsa until combined. 

5. Then, gently pour the quinoa into the vegetable mixture in the cast iron skillet. Stir everything together until it’s well combined. 

6. Top the casserole with shredded cheese. Place the casserole under the broiler and let the cheese get golden and bubbly. This should take about 4 minutes but could vary depending on your broiler. 

Make sure you do not walk away during this part of the cooking process. Cheese can go from bubbly to burn in a matter of seconds so I like to have my oven cracked open while I keep an eye on the cheese as it cooks. 

7. After the cheese is brown and bubbly, take your casserole out of the oven and you are ready to serve. If you want to garnish the casserole with avocado and/or green onions, feel free to do so now. Serve this casserole immediately so the cheese is nice and ooey-gooey.

Expert Tips

• ​​If you don't have a cast iron skillet, you can use a pan that can be transferred directly to the oven.
• While this is a vegetarian-friendly dish on its own, you can choose to serve this as a side dish and pair it with your favorite meat-based protein.
• For extra flavor in your quinoa, cook with vegetable stock instead of water for an extra kick of flavor.
• To make a quick transition from vegetarian to vegan, simply remove the cheese from the recipe. You can also opt to use vegan cheese.