Caramelized Leek, Fennel & Onion Gratin
This Caramelized Leek, Onion & Fennel Gratin is an easy one pan side dish that is creamy and so delicious. It’s a great Vegan and Whole30 gratin to serve at your next family meal, everyone will love it without realizing it’s dairy free.
Let’s be honest, when it comes to side dishes gratin has got to be high up on most people’s list. A creamy sauce, tender vegetables and a crunchy top, it’s just too good to resist.
Unfortunately if you are on a Dairy Free or Paleo diet, gratin which is usually packed with cream, cheese and butter, is strictly off limits.
Enter this decadently rich and creamy Vegan and Whole30 gratin that tastes like it is packed with dairy! Plus by swapping potatoes for leeks, fennel and onions, the dish has a delicious caramelized flavour.
I originally tried making this Leek, Onion & Fennel Gratin with coconut cream, but really struggled to mask the sweet coconut flavour which overpowered the dish, so I switched to my favourite vegan cream substitute, cashews. The sauce is so creamy and delicious that you would never know it doesn’t actually contain any dairy. Just make sure that you use a high speed blender or NutriBullet so that the cashews completely break down and there are no little bits remaining.
Although you could put the vegetables in raw and let them bake in the sauce in the oven, I love the caramelized flavour they develop when first cooked on the stove top. I find that this also makes the dish quicker to prepare and removes any of the uncertainty of whether the vegetables are fully cooked through after baking.
I think this vegan gratin would be a fantastic addition to any Thanksgiving dinner. You could prepare this dish up to 2 days in advance by sautéing the vegetables and making the cashew cream and then simply combine them together and bake the day of.
Here are a few other side dishes that you might enjoy:
- THE BEST Cauliflower Mash
- Roasted Fennel with Garlic & Herbs
- Lemon Roasted Green Beans with Almonds & Shallots
- Roasted Radishes
- Asian Brussels Sprouts
- Sheet Pan Roasted Brussels Sprouts, Butternut Squash, Bacon & Red Onion
If you make this recipe let me know in the comment section below, I would love to hear what you think or take a photo and tag me (@everylastbite_) on Instagram, I love seeing your photos!
Caramelized Fennel, Leek & Onion Gratin
Ingredients
- 2 tbsp olive oil/coconut oil
- 3 leeks thinly sliced
- 2 white onions thinly sliced
- 2 small fennel thinly sliced
- 2 cloves garlic crushed
- 1/4 tsp salt
- 1/2 cup cashews soaked in boiling water for 10 minutes
- 3/4 cup almond milk
- 1 tbsp dijon mustard
- 1/2 tsp pepper
- 2 tbsp nutritional yeast (sub for 1/4 cup parmesan if on SCD)
- 1 cup vegetable/chicken stock
- 1 tsp fresh thyme
Instructions
- Preheat the oven to 175 degrees Celsius (350 degrees Fahrenheit)
- In a high speed blender add the drained cashews and almond milk and blend until completely smooth. Pour the mixture into a pot and add in the mustard, pepper, nutritional yeast (or parmesan) and stock. Leave to simmer for 5 minutes or so until the liquid begins to thicken. It should coat the back of a spoon. Stir in 1 tsp fresh thyme
- In a cast iron skillet heat the oil on medium heat and then add in the leeks, onion, fennel and garlic. Sprinkle with salt and leave to cook for 10 minutes, until they become soft, slightly caramelized and golden in colour.
- Pour the cashew cream into the skillet and stir through so that it coats all of the vegetables. Transfer the skillet to the oven and bake for 20 minutes until bubbly and golden on top.
- Before serving sprinkle with fresh chopped parsley or thyme.
Nutrition
This is absolutely ridiculous deliciousness!!!! So good and pretty easy!
This was absolutely delicious! I made it for a dinner party, with a vegan holiday roast and roasted sweet potatoes and everybody loved it and raved about it The gratin was my favorite part of the meal AND the leftovers warmed up beautifully the next day and were absolutely delicious for lunch! I really like that it was absolutely perfect as is and I didn’t even need to tweak anything.
what can I use in place of the ground almond sauce
Delicious! Made this for our Christmas supper. The flavor only gets better for leftovers…ate with soft fried eggs for breakfast the following week.
This was a hit on Thanksgiving! Made some veg ‘sausage’ too and that accompanied this nicely. It also introduced me to fennel…I never used it before! This is pretty versatile in that you can eat it alone or it can go with so many other things, I even topped a pizza with some of the leftovers. Yum!
DELICIOUS. Love this recipe, cannot get enough! Thank you!
Whoa, seriously good stuff. The sauce is fantastic and can be used for all sorts of dishes including pasta, cauliflower, potatoes, etc. I added a bit of vegan Worcestershire sauce, which I think brightens it a bit. I could not get the nice browning shown in the photos even using the convection oven, but it did brown up with my butane torch. The broiler might also work.
Hello,
I love your recipes. I am not dairy free and am wondering what I could use instead of cashews and almond milk? Cheese and milk? If so, how much?
My husband is allergic to nutritional yeast, do you think it’ll taste fine without that or is there a good substitute besides real cheese?
YUM!!! Made this tonight and it was sooo good. I’m just shoveling it down my throat. haha. My husband is going Whole30 (I’m sitting this one out) and wanted something more indulgent feeling but still compliant. This was perfect! I will be making this again, for sure.
Hi, what can I use instead of Almond milk? Live in Ireland and I don’t like using ingredients that have a large carbon footprint.
Coconut milk or any other type of milk substitute would work well.
Coconuts do not exactly grow in abundance in Ireland
Oat milk is a pretty good substitute and should be travelling less.
My goodness, this is lush!!
Amazing sauce that I’ll use again over cauliflower or broccoli!
Yum!
Thanks!
This looks so good! Im hoping to make it for my upcoming friendsgiving. Do you think a vegan cream cheese sauce would work with this recipe? or making a roux and adding vegan cheese? Thanks!!
Tried this and it was a hit with my vegan husband and non vegan kids.
I made this for the first time tonight and will be adding it to our side dish rotation. It wasn’t hard to put together and it’s got wonderful flavors. I love that you can get such great tasting results with vegetables and a dairy free sauce!! Thank you!!
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I made this tonight, exactly as you suggested. We loved it! Who needs dairy anyway? 😉 Thank you!
Awesome! So happy to hear it was a success! And I totally agree, love when dairy free dishes are that creamy and delicious 🙂
I made this tonight. It was delicious, but a little too oniony for me. Maybe only 1 onion next time?
I’ll definitely be trying it again!
You could definitely reduce the amount of onion or sub it for more fennel or leeks.
Can you bake this in a 9×13 baking dish? Should I double the recipe? Making this for Thanksgiving and there’s about 15 of us.
Yes you can! For 15 I would double if not triple the recipe. Leftovers are great so it never hurts to make extra.
Would you triple the recipe for a 9×13 Pyrex, or do you think you’d need to make it in a bigger pan? Thanks in advance — planning to make this tonight!
Do I assemble veggies and sauce together if I am making it ahead of time ?
It depends on how far in advance, day of I would store them together, but a day or two ahead of time I would store them separately.
Thanks. Can I put the mixture in a different dish when I bake it rather than the pan I cooked the veggies?
Yes definitely, you could cook it on the stove top in a pan and then transfer to an oven proof dish, I just hate washing dishes 🙂
This looks so good! Could I use coconut cream and coconut milk (if I don’t mind the flavor) since I can’t have nuts?
Yes if you don’t mind the taste of coconut then you could definitely use it instead.