Skinny Sweet Potato Gratin tastes decadent yet is light, gluten-free and easily made dairy-free. A great swap for heavy holiday dishes!
Craving something light and healthy for the Thanksgiving table this year? Give m my low-fat, full-flavored, gluten and dairy-free Skinny Sweet Potato Gratin side dish a try!
Mashed potatoes are a staple at Thanksgiving, of course, but sweet potatoes have their place too. My Mother-in-Law LOVES sweet potatoes and always has a small mashed dish of them at Thanksgiving for her and me to eat. I had her in mind when making this layered dish using the bright and colorful veggie.
Usually gratins are made by layering sliced vegetables with heavy cream and cheese, but I kept the concept of layering and nixed all the heavy stuff. Sliced sweet potatoes sandwiching a layer of herbalicious caramelized onions are drizzled with a creamy sauce made from ALMOND MILK (or cow’s milk, if you feel more comfortable!) then blanketed under a crispy, crunchy, gluten-free bread crumb topping and baked.
Sweet, savory, creamy, crunchy – this gratin has all the flavor of a decadent-tasting, diet-busting holiday dish yet is low in fat, and a dish you can take seconds of totally guilt free. Indulging in buttery, cheesy side dishes at Thanksgiving is something I always look forward to, but it’s nice to have a healthy ally at the table!
Start by making the caramelized herbed onions that are spread between layers of tender sweet potato in the gratin. That’s just sweet onions sauteed with dried thyme, fresh sage, minced garlic, salt, and pepper until sweet and caramelized. Easy and so flavorful.
To the caramelized onions, add 1 cup milk then stir to combine. Most gratin recipes call for heavy cream or half and half but this recipe tastes just as decadent and is made with unsweetened almond milk! If you want to use cow’s milk, I recommend using 2% or higher milk fat.
Season the milk with plenty of salt and pepper then simmer until the sauce is just slightly reduced, 2-3 minutes, and set aside.
Meanwhile, get your sweet potatoes prepped. You’ll need 3lb sweet potatoes that have been scrubbed then peeled. Try and buy sweet potatoes that are all generally the same size in diameter so they’ll cook evenly in the gratin.
Next slice the sweet potatoes into 1/4″ slices. I used the slicing blade of my food processor to get perfectly uniform slices, though you could use a mandoline, or a very sharp knife.
If you’re still trying to decide if you want to make room for a food processor in your kitchen, slicing foods lickity split is reason enough for me. It took all of 45 seconds to slice 3lbs of sweet potatoes!
Here’s the food processor I have!
Spray the bottom of a 9×13″ baking dish with nonstick spray then line half the sweet potatoes into tight, overlapping lines in the bottom of the dish, and then season generously with salt and pepper.
Using a slotted spoon strain the caramelized onions from the milk then spread on top of the sweet potatoes. Layer the remaining sweet potatoes on top, season again with salt and pepper, then drizzle the remaining milk over the top. It will feel like there’s not enough sauce, but it’s ok!
Cover the baking dish with foil then bake for 20 minutes at 350 degrees. Remove the foil then bake for another 15 minutes, or until a knife inserted into the sweet potatoes goes in fairly easy. You don’t want the potatoes to be mushy or too soft at this point, but if they’re still hard, keep baking for another 5-7 minutes.
Meanwhile, make the crunchy gluten-free bread crumb topping – my favorite part! You’ll need 3/4 cup fresh gluten-free bread crumbs which I made by pulsing 3 slices of GF bread in a mini food processor. If you don’t need to eat GF, you can just use regular bread. Letting the bread slices sit out for an hour or even overnight will help make it easier to grind into course crumbs.
Add the breadcrumbs to a skillet with 1 Tablespoon butter or Earth Balance Vegan Butter (to keep the dish dairy-free,) 1 Tablespoon minced sage, and a pinch of salt, then toast until golden brown. Let the mixture cool slightly than pour into a bowl and mix in 1/4 cup freshly grated parmesan cheese (skip if dairy-free.)
Top the sweet potatoes with the bread crumb topping then bake for another 10-15 minutes or until the sweet potatoes are tender and the breadcrumbs are golden brown. Let sit for 10 minutes to thicken up, then slice and serve!
Perfectly, naturally sweet with a delectable caramelized onion layer, and savory herb and bread crumb topping – Mmm, mmm, MMM! Healthy Thanksgiving side dishes do not get better than this. I hope you enjoy!
Equipment
Ingredients
- 1 Tablespoon butter or vegan butter
- 1 Tablespoon extra virgin olive oil
- 1 jumbo sweet onion, chopped
- 1/4 teaspoon dried thyme
- 3 cloves garlic, minced
- 2 Tablespoons minced fresh sage
- 1 cup unsweetened almond milk, 2% or higher recommended if using cow's milk
- salt and pepper
- 3 lb sweet potatoes, ~4 medium and the same size, sliced 1/4" thick
For the bread crumb topping:
- 1 Tablespoon butter or vegan butter
- 1 Tablespoon minced fresh sage
- 3/4 cup fresh gluten free bread crumbs, made from 3 slices GF bread
- salt
- 1/4 cup freshly grated parmesan cheese, omit if dairy-free
Directions
- Melt butter and extra virgin olive oil in a large skillet over medium heat. Add onions, season lightly with salt, then saute until starting to become tender, 10 minutes. Add dried thyme then continue to saute until onions are very tender and slightly caramelized, 15-20 minutes, stirring occasionally. Add garlic and sage then saute until garlic is fragrant, 2-3 minutes.
- Add milk to the skillet, season generously with salt and pepper, then turn heat up to bring mixture to a bubble. Turn heat back down to medium then simmer until milk is just slightly thickened, 2-3 minutes (don't over-reduce.) Set aside.
- Preheat oven to 350 degrees then spray a 9x13" baking dish with nonstick spray. Layer half the sweet potatoes in tight rows in the bottom then season with salt and pepper. Using a slotted spoon, strain the onions from the milk then scoop onto potatoes and spread into an even layer. Top with remaining potatoes, season with salt and pepper, then drizzle reserved sauce on top (there won't be much.) Cover dish with foil then bake for 20 minutes. Remove foil then bake for 15 more minutes. Potatoes should be crisp tender when inserting a knife into them - if they're still hard, bake for another 5 minutes.
For the bread crumb topping:
- Rinse then dry skillet used for sauce then place over medium-heat. Melt butter then add sage, bread crumbs, and a little salt. Saute until lightly toasted them add to a bowl and, once slightly cooled, stir in parmesan cheese (if using.)
- Sprinkle bread crumb mixture on top of sweet potatoes then bake for an additional 10-15 minutes or until bread crumbs are evenly toasted and sauce is bubbly. Let dish sit for 10 minutes then serve.
Notes
- Use the slicing blade on your food processor or a mandolin to get even 1/4" slices of sweet potato.
Nutrition
Nutritional values are estimates only. Please read our full nutrition information disclaimer.
Did you ever try baking the sweet potato au gratin in muffin tins. It should be much easier to serve.
Could you make and refrigerate everything but the bread crumbs the night before? Then bake and add bread crumbs as written.
I *think* it would work though I don’t know if raw sweet potatoes soak liquid up. That would be my only concern!
Just wanted to let you know that I made these for our Thanksgiving dinner and they were perfect. I don’t think I’m going the sweet way again. The savory won over my taste buds and everyone else.
I’m so glad to hear it, Kyra! Thanks for the great feedback!
I made this last night as a side dish for our leftover turkey and it was completely amazing! I can’t wait to make it again :)
I’m so glad to hear it, Lauren!