• roasted cauliflower gratin

Roasted Mushroom, Cauliflower & Rainbow Chard Gratin

Fall is the smell of roasting vegetables. At least in my kitchen. And this roasted mushroom and cauliflower gratin mixed with sauteed onions and Rainbow Chard really puts me in that happy place where I can picture myself with a big bowl of hearty roasted veggies and crunchy, cheesy topping curled up in a chair next to a fire and reading a book. Okay that might not actually happen. More likely I’ll be eating big spoonfuls out of the pan as I dash off to my kid’s soccer game or basketball practice. But still….a girl can dream.

Starting with roasting the mushrooms and cauliflower brings out the nuttiness of the cauliflower and the earthy flavor of the mushrooms. You really want to get that golden brown, caramelized color on the cauliflower and the mushrooms. The Rainbow Chard (Swiss Chard) is a green leafy veggie so you don’t want to roast it. It is pretty hearty and has a milder flavor than spinach and adds a nice fresh element to this dish. I removed the leaves from the stems and chopped them up and sauteed them until just wilted in a bit of olive and butter with onion and garlic. You don’t want to overcook the Chard or it will be soggy in texture. Then the mixture gets added to the roasted cauliflower and mushrooms right in the pan and then topped with some heavy cream, a bit of cheese, and a crunchy almond and fresh thyme breadcrumb mixture. The veggies are all cooked through so baking is just for a few minutes to bring together the flavors and let the cream soak in and the topping get crunchy.

And, best of all, if you’re looking for a good make-ahead dish, whether for Thanksgiving as a side dish or a quick weeknight dinner, this one could be an ideal choice. You can straightaway purchase the mushrooms from online stores like Organic Mushroom Supplies, assemble everything else ahead of time, and then bake them just before serving. It’s also vegetarian, which could be convenient if you have any vegetarian friends or family members visiting for the holidays. It can be difficult to find a good, hearty dish for them to eat where they won’t miss the meat.

Here’s the step by step on how to pull together this delicious roasted mushroom, cauliflower, and rainbow chard gratin:

gratin ingredients

Ingredients for Roasted Mushroom Cauliflower and Swiss Chard Gratin

Preheat the oven to 400 and grab a rimmed baking sheet. Start by cleaning the mushrooms with a damp paper towel and remove the stems. Slice into equal pieces about 1/4 inch thick and place on the baking sheet.

cleaning mushrooms

Clean the mushrooms

Then slice the core from the cauliflower head and slice the florets into pieces about the size of the mushrooms. See picture below.

Breaking down the cauliflower

Breaking down the cauliflower

Arrange the mushrooms and cauliflower in a single layer on the baking sheet. Then drizzle with 3 Tablespoons olive oil and sprinkle with salt and pepper. Top with 8 -10 sprigs of fresh thyme.

Lay mushrooms and cauliflower in a single layer

Lay mushrooms and cauliflower in a single layer

Place in the oven and roast for 15 minutes and then turn. Continue to roast for another 10 and then remove the mushrooms.

Mushrooms and cauliflower ready for roasting

Mushrooms and cauliflower ready for roasting

Place the cauliflower back in for another 5-10 minutes or until caramelized. Remove and discard thyme sprigs.

Roasted mushrooms and cauliflower

Roasted mushrooms and cauliflower

Set aside and move on to the greens. Reduce oven to 350 if baking gratin to serve right away.

Roasted cauliflower

Roasted cauliflower

Remove the Swish Chard leaves from the stems and chop.

Remove Chard from the stems

Remove chard from the stems

chopped chard

Chopped chard

In a large sauce pan heat 1 Tablespoon of the unsalted butter with the last Tablespoon of olive oil. When melted…

Melt butter and olive oil

Melt butter and olive oil

Add in the onion, garlic, and a pinch of crushed red pepper flakes. Season lightly with salt and pepper and cook until softened – 3-5 minutes.

Onion, garlic, and crushed red pepper flakes

Onion, garlic and crushed red pepper flakes

Then add the chopped Chard to the pan and stir with a wooden spoon. It will begin to wilt and cook down. Don’t over cook. You just want to soften it and then remove it from the heat.

chopped chard in the pan

Chopped chard in the pan

wilted chard

Wilted chard

Now it’s time to butter a 9 x 13 baking dish and start layering in all this goodness. Just spread it out evenly with your hands.

roasted mushroom and cauliflower

roasted mushrooms and cauliflower in the baking dish

Add the wilted chard and onion mixture and spread evenly.

add wilted chard

add wilted chard and onion mixture

Time to add the heavy cream….



Then the cheese…..

sprinkle with cheese

Sprinkle the cheese over the top in an even layer

Time to make the crumbly topping. Start with slivered blanched almonds and them to a food processor and pulse until they resemble breadcrumbs.

Add blanched almonds

Add blanched almonds to food processor

Pulse almonds

Pulse until the size of breadcrumbs

Add to a bowl with the Panko breadcrumbs and add in the leaves of 4 or 5 sprigs of fresh thyme.

add almonds to breadcrumbs

Add to bowl with Panko breadcrumbs

Almond Thyme breadcrumb mixture

Almond Thyme Breadcrumb mix

Add that final layer of yummy, crunchy almonds and breadcrumbs and thyme on top of the veggie gratin. Drizzle with olive oil so that the breadcrumbs get nice and brown and bake in a 350 degree oven for 20 minutes then place under the broiler for 2-3 minutes to get the top golden brown. Serve warm.

top gratin with almond breadcrumbs

Top gratin with the almond breadcrumb mixture

Print Friendly, PDF & Email

Roasted Mushroom, Cauliflower, and Swiss Chard Gratin

Roast Time: 25 mins
Bake Time: 20 mins
Serves: 6 people


  • 8 oz Crimini mushrooms
  • 1 head cauliflower
  • 1 bunch Swiss Chard or Rainbow Chard
  • 12 -14 sprigs fresh thyme
  • 2 large cloves garlic, minced
  • 1 medium yellow onions, diced (approx 2 cups)
  • pinch red pepper flakes
  • 2 Tablespoons unsalted butter, divided
  • 4 Tablespoons extra virgin olive oil, divided (plus drizzle for top of gratin)
  • 1/2 cup shredded 3-cheese blend (Romano, Asiago, Parmesan) or just Parmesan
  • 1/2 cup heavy cream
  • 1/3 cup slivered blanched almonds
  • 1/4 cup panko bread crumbs
  • Kosher salt and ground pepper


  1. Pre-heat oven to 400. Clean mushrooms with a damp paper towel and remove stems and dice into 1/4 inch thick slices. Remove cauliflower from the stalk and slice florets to match the size of the mushrooms. Drizzle with 3 Tablespoons olive oil and season with salt and pepper. Top with 8-10 sprigs fresh thyme. Bake for 15 minutes, turn veggies, then another 10. Remove mushrooms after 25 minutes and bake cauliflower for 10 more minutes, if needed. Remove from oven and discard thyme stems. Reduce oven to 350.
  2. Remove Swiss Chard from the stems and chop. In a large sauce pan heat 1 Tablespoon unsalted butter and 1 Tablespoon olive oil and then add in the onions, garlic, pinch of red pepper flakes, and season with salt and pepper. Saute for 3-5 minutes, until softened. Add in the chopped chard and cook until just wilted. Remove from heat.
  3. Grease a 9 x 13 inch baking dish with the last tablespoon of unsalted butter and layer in the mushrooms and cauliflower and then the swish chard and onion mixture. Pour on the cream, then sprinkle with cheese.
  4. Make the almond breadcrumb thyme topping by pulsing the slivered almonds in a food processor and adding to a bowl with the breadcrumbs. Stir to combine and then add in the leaves of 5-6 sprigs of fresh thyme.
  5. Top the gratin with the almond breadcrumb thyme mixture and drizzle with olive oil. Bake for 20 minutes and the put under the broiler for the last 2-3 minutes to brown. Serve warm.

User Rating

4 (3 Votes)



You May Also Like

No Comments