This Cheesy Vegetarian Casserole is a tasty meatless dinner for everyone who likes broccoli, mushrooms, brown rice, and cheese. And this tasty casserole could also be a side dish.

PIN Cheesy Vegetarian Casserole to try it later!

Cheesy Vegetarian Brown Rice Casserole close-up photo of finished casserole

It took me a couple of dump-in-the-trash attempts to get this Cheesy Vegetarian Casserole to come out the way I wanted it, but immediately after I finished taking these photos I sat down at the island in my kitchen and devoured the little plate of casserole you see here, so I think experimenting with the recipe was worth it.

The version that worked has a few steps that might seem labor intensive, like cooling the rice, reducing the broth, and cooking the mushrooms, onions, and broccoli separately before they get combined into the casserole. Nobody likes a simple recipe more than me, but I do think it’s those little touches that helped me get the result I wanted, so I hope people will trust me on the extra steps.

What ingredients do you need for this recipe?

  • uncooked brown rice, I used Uncle Ben’s Brown Rice (affiliate link)
  • canned vegetable broth
  • mushroom stock cubes (affiliate link), optional, but recommended
  • mushrooms
  • onion
  • broccoli
  • olive oil
  • Italian Herb Seasoning (affiliate link)
  • salt and fresh ground black pepper to taste
  • sour cream
  • grated sharp cheddar
  • grated Four Cheese Mexican Blend
  • grated Mozzarella

Can you use different vegetables for this vegetarian casserole?

If broccoli isn’t going to be a hit at your house, you can switch that out for another green vegetable like green beans.

Can you use different types of cheese?

I used three types of cheese for lots of cheesy flavor, but you can definitely switch out the cheese for different cheese if you prefer something else.

Weekend Food Prep:

This recipe has been added to a new category called Weekend Food Prep to help you find recipes you can prep or cook on the weekend and eat during the week! And this cheesy vegetarian casserole recipe makes a generous 8 servings (or 10 side dish servings) so you’ll have some to stockpile in the freezer for another day when you don’t want to cook!

Cheesy Vegetarian Brown Rice Casserole process shots collage

How to Make Cheesy Vegetarian Brown Rice Casserole:

(Scroll down for complete recipe with nutritional information.)

  1. Cook 1 1/2 cups brown rice to get about 4 1/2 cups cooked brown rice. (I used Uncle Ben’s Brown Rice and used my beloved Zojirushi Rice Cooker (affiliate link) to cook the rice.
  2. When the rice is done (very important!) spread it out on a baking sheet and let it cool. (If you skip this step, the rice will keep cooking as it cools and will be too soft in the finished casserole.) Put the rice in a large bowl when it’s cooled.
  3. While the rice cooks put one can vegetable broth into a small saucepan and let it simmer over medium-low heat.  If you have some mushroom base (affiliate link), add about a tablespoon to the stock before you simmer, but the mushroom base is not essential. (You can also use mushroom stock cubes (affiliate link).) Simmer the stock and mushroom base until it’s reduced to one cup.  Let cool. 
  4. While the broth simmers chop the mushrooms, onion, and broccoli. Saute the mushrooms in a little olive oil and add to the bowl with the rice.
  5. Saute the onions in a little more olive oil until they start to brown; then add the Italian Herb Blend (affiliate link) and cook about a minute more.  Add the seasoned onions to the bowl.
  6. Cut up the broccoli stems into small slices and flowerets into small pieces until you have 4 cups chopped broccoli. Microwave broccoli 1 1/2 minutes (or saute if you don’t have a microwave), drain, and add to the bowl.
  7. Gently mix together the rice, mushrooms, seasoned onions, and broccoli.
  8. Whisk the sour cream into the reduced and cooled broth, then mix in 1 1/2 cups of the grated cheese. (I used the same measuring cup I microwaved the broccoli in to save washing another dish.)
  9. Pour the sauce/cheese mixture over the rice mixture and gently combine, until all the ingredients are slightly moistened.
  10. Spray a 9 inch by 13 inch casserole dish (or comparable size) with non-stick spray and put the rice mixture in the dish, spreading it out so it’s even.  Sprinkle the rest of the cheese over the top.
  11. Bake uncovered for 35 minutes, or until the casserole is bubbly and nicely browned on top.  Serve hot.

Cheesy Vegetarian Casserole shown with one serving on plate and casserole in serving dish

More Tasty Vegetarian Dinners to Try:

Instant Pot Mexican Beans
Slow Cooker Vegetarian Greek Lentil Casserole
Macaroni with Greens, Lemon, and Parmesan

Cheesy Vegetarian Brown Rice Casserole close-up photo of finished casserole
Yield: 8 servings

Cheesy Vegetarian Brown Rice Casserole

Prep Time 45 minutes
Cook Time 35 minutes
Total Time 1 hour 20 minutes

Cheesy Vegetarian Brown Rice Casserole is a perfect vegetarian main dish or side dish, especially for people who like cheese!


  • 1 1/2 cups uncooked brown rice (see notes)
  • one 14 oz. can vegetable broth, simmered to reduce
  • 1 T mushroom base (optional, but recommended)
  • 12 oz. mushrooms
  • 1 large onion
  • 4 cups chopped broccoli
  • 2 tsp. + 2 tsp. olive oil
  • 2 tsp. Italian Herb Blend
  • salt and fresh ground black pepper to taste
  • 1 1/2 cups sour cream
  • 1 cup grated sharp cheddar
  • 1/2 cup + 1/2 cup grated Four Cheese Mexican Blend
  • 1/4 cup grated Mozzarella


  1. Cook rice according to package directions to get about 4 1/2 cups cooked brown rice. I used my beloved Zojirushi Rice Cooker (affiliate link) to cook the rice.
  2. Spread hot rice out on a cookie sheet to cool while you prep other ingredients.  As soon as rice is cool, transfer it to a large bowl (big enough to hold all the ingredients.)
  3. While rice cooks, put the stock (and mushroom base (affiliate link) if using) into a small saucepan and simmer to reduce the amount to 1 cup.  (This concentrates the flavor, don’t skip this step.)  Let stock cool.
  4. Chop mushrooms into pieces about 1/2 inch big, and chop onion into small pieces.
  5. Cut up the broccoli, chopping stems and cutting flowerets into small bite-sized pieces so you have 4 cups chopped broccoli.
  6. Preheat oven to 375F/190C.
  7. Heat 2 tsp. olive oil in a large non-stick frying pan, add mushrooms and saute over medium-high heat until they’re lightly browned and all liquid is evaporated, about 5-6 minutes. Put mushrooms in the bowl with the cooled rice.
  8. Heat the other 2 tsp. olive oil, add onions, and cook over medium-high heat until the onions are starting to brown, about 4-5 minutes. Add Italian herb blend (affiliate link) and cook 1 minute more. Add the seasoned onions to the bowl with the rice.
  9. Put the broccoli in the microwave and cook 1 1/2 minutes at high power. (Or you can saute the broccoli for 2-3 minutes in the pan.) Drain broccoli and add to the rice.
  10. Gently combine the rice, mushrooms, onions, and broccoli in the bowl.
  11. Whisk together the sour cream and cooled stock; then stir in 1 cup grated sharp cheddar and 1/2 cup Four Cheese Mexican Blend.  Gently stir the sauce and cheese mixture into the rice mixture and combine until all the ingredients are coated with sauce.
  12. Spray a 9 inch by 13 inch glass or crockery casserole dish (or comparable size) with non-stick spray and spread the casserole mixture into the dish, patting it down with the turner so it’s even.  Sprinkle with the other 1/2 cup Four Cheese Mexican Blend and the 1/4 cup grated Mozzarella.
  13. Bake casserole uncovered until it’s bubbling and the top is lightly browned, about 35 minutes.  Serve hot.


I use Uncle Ben’s Brown Rice for this recipe. Use reduced-fat or full-fat cheese, whichever you prefer.

This Cheesy Vegetarian Brown Rice Casserole freezes well.  Thaw in the refrigerator and heat in microwave or in a covered baking dish in the oven or toaster oven. It will also keep in the fridge for several days.

Recipe created by Kalyn.

Nutrition Information:



Serving Size:


Amount Per Serving: Calories: 370Total Fat: 25gSaturated Fat: 13gTrans Fat: 1gUnsaturated Fat: 8gCholesterol: 70mgSodium: 566mgCarbohydrates: 22gFiber: 5gSugar: 5gProtein: 16g

Nutrition information is automatically calculated by the Recipe Plug-In I am using. I am not a nutritionist and cannot guarantee 100% accuracy, since many variables affect those calculations.

Did you make this recipe?

Did you make this recipe? Please leave a star rating (under the PRINT button in the recipe) or share a photo of your results on Instagram! THANKS!

Cheesy Vegetarian Brown Rice Casserole square image of finished casserole

Low-Carb Diet / Low-Glycemic Diet / South Beach Diet Suggestions:
With brown rice, low-fat sour cream, low-fat cheese, and a generous amount of vegetables, this Cheesy Vegetarian Brown Rice Casserole would be suitable for Phase 2 or 3 of the original South Beach Diet. This would be too high in carbs for a low-carb diet plan.

Find More Recipes Like This One:
Use Casseroles to find more recipes like this one. Use the Diet Type Index to find recipes suitable for a specific eating plan. You might also like to Follow Kalyn’s Kitchen on Pinterest to see all the good recipes I’m sharing there.

Historical Notes for this Recipe:
This recipe was posted in 2014. It was last updated with more information in 2021.

Pinterest image of Cheesy Vegetarian Casserole

Share This: