Mexican Casserole is a crowd-pleasing favorite the whole family will love! It’s made with a simple base of homemade polenta and then hearty beans, corn, salsa, spices, lime and fresh cilantro. Finish with a generous layer of Monterey Jack cheese.
Serve with your favorite tortillas, and top with sour cream and avocado.
Not only is this Mexican Casserole easy to make but it freezes beautifully and serves up a delicious meal. I can’t remember for the life of me where I first read about vegetarian Mexican casseroles or even where the bare bones of this recipe originated, but it doesn’t really matter. This has been a staple in my recipe box for several years now and will always be a favorite.
What I love About This Recipe
- It freezes super well! I’ve gifted new mommies and grieving friends with this freezer meal, a bag of tortilla chips, a small container of sour cream, and an avocado. ALL have appreciated the flavors.
- Homemade polenta base. The best part about this casserole is the homemade polenta at the bottom. It’s a soft boiled dough made from coarse ground yellow corn. When cooled, it thickens into a sweet and salty base for our baked casserole.
Mexican Casserole Key Ingredients
Salsa: Choose a thick salsa to avoid too much liquid in this recipe.
Cornmeal: To make polenta you want to look for a high quality cornmeal. Course cornmeal will take longer to create the polenta than fine cornmeal.
Monterey Jack Cheese: Make sure to grab this kind of cheese for your top layer. It has the best flavor for this combination of ingredients. Don’t use cheddar or mozzarella – it won’t be as good!
How To Make The First Layer of Polenta
It sounds tricky, but homemade polenta is actually very simple to make. The polenta needs only quality cornmeal, water, salt, sugar and butter.
- Start by bringing 3 cups of water to boil in a large pan. As soon as the water boils, add 1 cup of cornmeal.
- Turn your heat to as low as you can to a bare simmer. We want the corn to cook and soak up most of the water. To help it out, whisk the polenta occasionally until thick.
- Add butter, granulated sugar, salt, and some cracked black pepper. Whisk it again and cook until the butter has melted the ingredients and are well incorporated. Remove from the heat.
Layers of the Mexican Casserole
- Make the polenta and spread as the base layer in a greased 9×13 deep baking pan.
- In a large bowl, combine all the remaining ingredients (except for the cheese) starting with the beans. You will add drained pinto beans, drained black beans, frozen corn (fresh is fine too!), your favorite salsa, diced tomatoes, chopped cilantro, red onion, garlic cloves, fresh lime juice cumin, oregano, and salt. Mix it all together!
- Pour your bean mixture on top of the polenta and top with 2 cups of shredded Monterey Jack cheese.
Baking and Freezing Instructions:
To freeze: Cover with heavy-duty foil and label with baking instructions. From freezer to oven, it will need to bake for 45 minutes in a 375˚ F oven or until the cheese is golden and the sides are bubbling. Cool for 10 minutes before serving.
To Bake Right Away: Bake in a 350˚ F oven for 45 minutes or until the internal temperature in the middle reaches 160˚F.
Enjoy!
Recipe Notes
Salsa: It’s best to use thicker salsa so that your casserole does not become too runny after it’s baked.
Make it your own. Feel free to add bell peppers, hot Mexican spices, or whatever you have in plenty.
Polenta Tips: You’ll need to watch the polenta to get it to the right consistency. If you use a finer grain of cornmeal your polenta will form within minutes. If you use a more coarse grain it could take up to 15 minutes. Just keep stirring occasionally over very low heat until it resembles thick mashed potatoes.
More Casserole Recipes
- Macaroni Casserole with Kielbasa Sausage – super simple and delicious!
- Broccoli and Cheese Casserole – more of a side dish.
- Chicken Rotini Casserole – family favorite!
Favorite Mexican Casserole Freezer Meal
Ingredients
First Layer (Polenta)
- 1 cup quality cornmeal
- 3 cups water
- 2 Tablespoons butter
- 1 teaspoon salt
- 1 Tablespoon sugar
- 1/8 teaspoon cracked black pepper
Second Layer
- 32 oz pinto beans drained
- 30 oz black beans drained
- 1 cup frozen corn
- 16 oz thick salsa
- 15 oz diced tomatoes drained
- 1/2 cup cilantro chopped
- 1/3 cup red onion chopped
- 2 garlic cloves minced
- 2 Tablespoons fresh lime juice
- 2 teaspoons cumin
- 1 teaspoons oregano
- 1/2 teaspoon salt
Third Layer
- 2 cups Monterey Jack Cheese shredded
Instructions
- To make polenta, bring 3 cups of water to boil in a large pan. Whisk in 1 cup of cornmeal. Turn the heat down to a bare simmer and cook for 15 minutes, whisking occasionally. Once thickened, whisk in to the polenta: 2 Tablespoons butter, 1 Tablespoon of granulated sugar, 1 teaspoon of salt and cracked black pepper. Cook for an additional few minutes until the butter is fully melted. Remove from heat.
- In a large bowl mix together 2 cans of drained pinto beans, 1 can of drained black beans, 1 cup of fresh or frozen corn, 1 - 16 oz. jar of thick salsa, 1 - 15 oz. can of drained diced tomatoes, 1/2 cup chopped cilantro, 1/3 cup chopped red onion, 2 minced garlic cloves, 2 T. fresh lime juice, 2 tsp. cumin, 1 tsp. oregano and 1/2 tsp. salt. Set aside.
- Spread the polenta at the bottom of a well-greased 13x9 baking dish. Next, spread your bean mixture onto the polenta and then top with 2 cups of shredded Monterey Jack cheese.
- To Bake Right Away: Bake uncovered 350˚ F for 45 minutes or until the internal temperature reaches 160˚ F. Let cool for 10 minutes before serving.To Freeze: Cover with heavy-duty foil, label, and freeze. From freezer to oven, bake for 45 minutes in a 375˚ F oven or until the cheese is golden and sides are bubbling. Cool for 10 minutes before serving.
Comments & Reviews
This was really good! I didn’t have corn so i diced up half a zucchini and nobody noticed! The polenta wasn’t quite firm enough when I served it, I should’ve let it cool longer – so the kids were put off by that. When i warmed up the leftovers it had firmed perfectly. It baked at 350, not frozen, for 30 min. Should I try 375 next time?
Hi Tiffany!
Thanks for the feedback! The polenta will harden up if cooled, but you could also add an extra 1/4 cup of cornmeal to it to make it thicker. I’m not sure what brand you used…Some cornmeals will create a softer polenta if the corn is ground more fine. And yes, I would suggest baking the casserole at 375, even when not frozen 🙂
How long do you bake it if you are not going to freeze it?
Hi Gretchen!
35 – 40 minutes should be plenty if the casserole is not frozen. Basically, you want it hot and golden with the edges bubbling.
Enjoy!