Go Back Email Link
baked fennel and sweet potato gratin in round casserole next to green napkin

Fennel & Sweet Potato Gratin

Print Recipe
Prep Time 30 minutes
Cook Time 1 hour
Total Time 1 hour 30 minutes
Servings 8 servings
Author Breathing and Cooking

Ingredients

  • 1 Tablespoon olive oil for drizzling
  • 1 1/2 Tbsp butter softened
  • 2 pounds assorted sweet potatoes peeled and sliced thin (1/8th inch or thinner)
  • 1 large fennel bulb sliced thinly crosswise
  • 1 1/4 * cup heavy cream
  • 3/4 cup shredded parmesan divided
  • 1/2 cup shredded gruyere
  • 2 teaspoons chopped fresh thyme
  • 1 Tbsp chopped fennel fronds plus additional unchopped fronds for garnish
  • 2 garlic cloves minced
  • Kosher salt and cracked pepper to taste I use about 1 1/2 teaspoons Diamond kosher and maybe 10 cranks of pepper
  • freshly grated nutmeg optional

Instructions

  • Drizzle a little olive oil over casserole dish and brush evenly over bottom and sides. Alternatively you could use cooking spray, set aside. Preheat your oven to 375°f.
  • Prep all of your ingredients, including putting your salt and pepper in a little bowl (it makes seasoning much easier when you're assembling the layers!)
  • Place sweet potatoes and sliced fennel in a large bowl and pour 1/4 cup of the cream over them. Sprinkle with a little kosher salt and cracked pepper and work the vegetables and cream together with your hands until the cream is thinly coating all of the vegetables.
  • Combine minced garlic with remaining cup of cream.
  • Set 1/4 cup of the parmesan aside and combine the remaining parmesan and gruyere in a bowl.
  • Arrange 1/2 of your vegetables with edges overlapping to cover the bottom of your casserole. Sprinkle with half of the thyme and chopped fennel fronds, 1/2 of the salt and pepper, 1/2 of the softened butter separated into little dabs with your fingers, 1/2 of the remaining cream and 1/2 of the combined cheeses. Repeat layers.
  • If you have extra slices of vegetables try to find places to tuck them into your layers doing your best to keep everything level so it cooks evenly. Use a rubber spatula to scrape any remaining cream from the bowl onto the top of your gratin. Garnish with some of the fronds from the fennel. I also really like to grate some nutmeg over top at this point, but that's optional.
  • Cover tightly with foil and bake 45 minutes. Test the center of the casserole with the tip of a sharp knife- the vegetables should be almost cooked through (tender with just a little resistance).If they seem at all hard, cover and cook another 10 minutes before proceeding.
  • Once vegetables are tender, uncover, sprinkle with remaining 1/4 cup parmesan and continue cooking another 15-20 minutes until top is golden and vegetables are meltingly tender.
  • If your top hasn't browned as much as you'd like place it under the broiler for a minute but watch very carefully and remove before it burns!
  • Let it rest 10 minutes before serving and enjoy!

Notes

  • Use more or less salt to your preference. My measurement is using Diamond Kosher salt, if you're using table salt or Mortons kosher salt you'll want to use less
  • The nutmeg is optional but I really love what it adds here. I grate nutmeg over mine but you can use ground nutmeg. If you're using ground nutmeg a little goes a long way!