Roasted Cauliflower & Mushroom Casserole
Gluten Free,  Low-Carb,  Salads & Side Dishes,  Vegetarian

Roasted Cauliflower & Mushroom Casserole

Roasted Cauliflower & Mushroom Casserole is a wonderful rustic side dish or vegetarian meal.  Roasting the cauliflower imparts a slightly sweet nutty flavor.

Roasted Cauliflower & Mushroom Casserole

I was staring into my veggie drawer and there smiling back at me was a head of cauliflower and a pound of button mushrooms.  Two weeks of eating very little carbs left me craving a casserole.  Discovering this recipe by The Iron You made me oh so happy.

Roasted Cauliflower & Mushroom Casserole

I can eat roasted cauliflower with the same enthusiasm I approach a big bowl of glorious Sage Brown Butter Popcorn (that was my not so subtle way of giving this amazing popcorn a shout out). 

It’s fabulous.  Roasted cauliflower and that popcorn.

Roasted Cauliflower & Mushroom Casserole

We enjoyed Roasted Cauliflower & Mushroom Casserole as a side and leftovers for lunch.  Another time I think I’ll add diced cooked chicken for a nice protein boost.

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All my best,
xo Libby

Roasted Cauliflower & Mushroom Casserole

Roasted Cauliflower & Mushroom Casserole

The Iron You
4.45 from 9 votes
Prep Time 30 minutes
Cook Time 40 minutes
Total Time 1 hour 10 minutes
Servings 6


  • 1 head of cauliflower cored and cut into florets
  • 1 lb. button mushrooms chopped
  • 1 large onion finely chopped
  • 2 sprigs fresh thyme leaves only, finely chopped
  • 2 garlic cloves finely chopped
  • 1 1/2 Tbl. olive oil
  • 1 tsp. sea salt
  • 2 large eggs
  • 1/2 cup sharp cheddar cheese shredded
  • 1/2 cup sour cream or Greek yogurt
  • 1/3 cup Parmesan cheese grated


  • Preheat oven to 425 degrees. Coat a medium baking dish with olive oil and reserve.
  • Spread cauliflower florets in a single layer on a large rimmed baking sheet; drizzle with 1 Tbl. oil olive and sprinkle with sea salt. Roast in oven for 30 minutes or until golden brown, turning once.
  • Meanwhile, in a large skillet over medium heat sauté the mushrooms in 1/2 Tbl. olive oil and a couple of pinches of salt. Stir every minute or so until mushrooms have released all their liquid. Add onion and thyme cook for another 4 – 5 minutes until translucent. Stir in garlic, cook for another minute and remove from the heat.
  • When the cauliflower has caramelized add to the skillet.
  • In a large bowl combine eggs, cheddar cheese, and sour cream. Add cauliflower mushroom mixture, stir until well combined. Pour into prepared baking dish. Sprinkle with Parmesan cheese and cover with foil.
  • Reduce oven temp. to 350 degrees. Bake casserole for 30 minutes covered, then remove foil and bake for another 10 minutes, until lightly browned around edges.


  • Mary Ann

    5 stars
    Thank you for this recipe. I made it pretty much as written, but without the eggs, and with a little extra yogurt. It was delicious. I served with sausages on the side. My hubby loved it, and went back for seconds. :) Will definitely add it to my roataion. I’m not sure we would have liked it as well if I had added eggs.

  • Karen

    5 stars
    I don’t usually comment on recipes but had to tell you that this has been one of my favorite recipes for the past 2 years. I’m trying to eat low carb I make it often as shown above with the addition of roasted broccoli along with the roasted cauliflower. Today, though, I was looking for a recipe with cauliflower, mushrooms and sausage and couldn’t find one that appealed to me so I decided to make this using ricotta cheese instead of sour cream and italian cheeses instead of cheddar along with some turkey italian sausage I wanted to use up. I layered it in the pan with spinach and it was incredible! I’m in my 70’s and alone so I like to make things I can eat and freeze and this recipe freezes well for other dinners. I just wanted to thank you for such an amazing recipe. I’m not much of a cook but this always turns out well and i’ve gotten compliments when I’ve served it to guests. Thanks again.

  • Taylor

    1 star
    This was DELICIOUS!!! I made it exactly to specs except I added bacon, used shiitake mushrooms, and didn’t add as much shredded cheese mainly because I didn’t have shredded and had to improvise with the little block cheese that I had LOL! My seven ya old LOVED IT! My husband couldn’t get enough of it either! I can’t wait to try this recipe with chicken! Oh I also didn’t have any thyme so I used parsley instead and it was still delicious! Bravo for this wonderful dish!!! BTW I give this a full 5 stars even though the actual rating stars won’t let me click that many for some reason!

  • Vic Olson

    Don’t add the eggs, they are unnecessary and they coagulate, creating an unappetizing appearance. It was not well received because of that. Otherwise, a great recipe.

  • Kathleen

    Delicious dish! I did not have sour cream or greek yogurt so I used ricotta cheese thinned with some milk. Used mostly parmaesan cheese and a little cheddar. I will make this again :-)

  • Ginzi Putzi

    5 stars
    Just made this tonight – so delicious! It was a hit with my husband and our fathers, so I am going to make it again for the family BBQ in two days. I saw the comment that someone’s “2-year olds” (plural!) loved it – let’s see if that works for my 4, 3 and 2 year old grandsons! By the way, I also added a little fresh chopped rosemary (great suggestion) and used a red onion as that was what I had on hand. Lovely subtle sweet flavour with the red onion.

    • libby

      Yay!! Happy to hear your family enjoyed this dish. Sounds like you’ve got a strong line of great eaters there. Thank you for sharing Ginzi.

  • Newbie

    5 stars
    I am relatively new to cooking so I have a rather basic question – can I use regular white mushrooms cut in half instead of button mushrooms?

    • libby

      Hello Newbie. Funny/ironic that I think we’re both referring to the same mushroom. I’m never sure what to call white/button mushrooms but they’re what I most often buy and have found them to work wonderfully in any recipe calling for mushrooms. Forge ahead my friend.

  • Jessie

    5 stars
    Delicious! The whole dish went, even my 2 year olds ate it! The only thing I did different was use half the onion and I added a little white pepper to the egg mixture before combining. Not sure if it even needed it!!

  • hannnah p

    5 stars
    I exchanged non fat greek yogurt for the sour cream and no cheddar cheese, ( I didn’t have either) but added a jar of marinated artichoke hearts.. i increased the parmesan cheese a bit.. and added a bit of asagio cheese. I”m sorry to the original cook that I changed it but thought it could help someone else!
    I doubled the thyme and added a pinch of chopped rosemary . Second time I had some spinach left over and I tossed it in. I think this recipe can be adapted to what you have on hand easily. Yay for the roasted cauliflower – we love it now.

  • Raymond

    4 stars
    I made this for the first time last night. As I speak there is very little of it left LOL. The idea of adding sea salt to baked cauliflower is a novel, (and delicious) one I would have never thought of that. I did everything the same except I added 2lbs ground beef.

  • Sha

    I have made this a few times now since your post in October, and this is a KEEPER! Thanks. The first time I kept true to your original recipe and wow was I blown away; the second time I added bacon, and the third time sausage. Each was mouth-watering savory, like flavor explosion, seriously. Leftovers keep well and also reheat well.

    • libby

      Love those additions Sha!! Thank you so much for taking the time to comment. May be time to revisit and picture a new version :)

  • Heather

    Oh my goodness. I cannot wait to try this. I am making this for dinner tomorrow and I am going to add the chicken to make it a whole meal. mmmmm. I am absolutely in love with your blog by the way. I am hooked! thanks so much!

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