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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
4.38 from 8 votes
Prep Time 30 mins
Cook Time 40 mins
Total Time 1 hr 10 mins
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.