Savory sweet potato puff pastry pie with caramelized balsamic onions and cheese.
If you like sweet potatoes, you will love this savory sweet potato puff pastry pie! It makes a perfect vegetarian main dish, one that you can definitely serve either for Thanksgiving or Christmas or any other autumn/winter celebration where you are in need of a main vegetarian main dish (if using the right kind of vegetarian cheese).
Over the years I have made quite a few sweet potato pies or casseroles, from the super-easy sweet potato gratin to pies with roasted vegetables, or with Gorgonzola.
I begin to think that I might have made a version of almost each savory sweet potato pie recipe I found in a cookbook or a magazine, this kind of pie is just so attractive to me...
This particular sweet potato puff pastry with balsamic onions is another version of a recipe I found in a magazine. Whenever we go on holiday with the car, I make a point of buying a recipe magazine at one of the gas stations we stop on the way. It's like a souvenir, every time I look into that magazine over the next few years, I remember during which trip I bought it. It's nice.
I've tweaked the recipe here and there to make it more suitable for us, and the main change was adding quite a lot of cheese. It was delicious! Those soft roasted sweet potatoes, the sweet and tangy balsamic onions and then that oozing cheese, this pie will definitely make you happy.
The ingredient list is not particularly long or expensive, all common and cheap ingredients, but the result makes you think that the pie is really something quite elaborate and expensive. It just looks so good!
- If you want to make it yourself, I am sure it would be wonderful, but I never bother, I like the one I am able to buy, it is delicious and so easy to work with.
- The most common type in Germany is the one found in the refrigerator section of the supermarket. It is already rolled which makes it even easier to work with.
- However, if all you can get is frozen, that is perfect as well. Just make sure you remember to thaw it in advance and read the packet's instructions before rolling it.
- One sheet of already rolled puff pastry here weighs 275 g/ 9.7 oz. After lining the gratin dish with the pastry, I had some scraps leftover, but not too many of them. So, between 250 g/ 8.8 oz and 275 g/ 9.7 oz will be fine.
- I used a mixture of white and red onions to make the caramelized balsamic onions, but if you only have one sort of onions, that will be fine as well.
- I like using Gruyere cheese for this kind of gratin, it is a nice melting type of Swiss cheese.
- If you can't get any Gruyere cheese, you can replace it with another kind of good melting cheese, the one you like best.
- However, if using Gruyere, keep in mind that this particular cheese is not technically vegetarian, as it is made using rennet, an enzyme taken from the stomach of calves. If you want to make this dish vegetarian, make sure you know which kind of melting cheese is suitable for vegetarians.
Otherwise, you will need the sweet potatoes, heavy cream some dried thyme and four eggs.
How to make?
- Making this roasted sweet potato pie is much easier than you might think. The only thing I think is good to have when making this or any other potato pie or casserole is a mandoline slicer (Amazon affiliate link). A mandoline will help you slice the sweet potatoes in really thin and regular slices, a job I find very difficult to achieve with just a knife, no matter how good that knife is.
- Slice the onions. Saute in olive oil, add balsamic vinegar, sugar, and thyme and cook for about 5 minutes more until they get soft and start to caramelize. Season and let cool slightly while you prepare the rest.
- Grate the cheese, then peel and slice the sweet potatoes thinly.
- Line the baking dish with the already rolled puff pastry or roll the pastry yourself. Cut off the excess pastry and pierce the crust all over using a fork.
- Arrange some of the potatoes in the baking dish, season them generously, sprinkle with some of the onions and cheese and repeat. End with a third layer of sweet potato slices.
- Mix together the eggs, cream, and milk. Season again and pour the mixture over the pie.
- Bake in the preheated oven for about 50 minutes or until the sweet potatoes are cooked through.
- If the roasted sweet potato pie with balsamic onions threatens to get too dark too soon, cover it loosely with a piece of aluminum foil, I did that after about 30 minutes cooking time.
How to serve?
- Enjoy with a green salad with vinaigrette or yogurt dressing.
- The pie is best served immediately.
- Lefovers can be easily reheated in the oven. However, keep in mind that the puff pastry might become slightly soggy after a while. It will still be delicious though.
More savory pies:
Sweet Potato Puff Pastry Pie
- 9 oz white or yellow onions 250 g
- 9 oz red onions 250 g
- 2 tablespoons extra virgin olive oil
- ½ teaspoon dried thyme
- 2 tablespoons sugar
- 6 tablespoons balsamic vinegar
- 1.3 oz sweet potatoes 600 g
- ¾ cup Gruyere cheese or a vegetarian alternative 150 g (Note 1)
- 10 oz puff pastry 275 g (Note 2)
- 2 eggs
- 1 cup heavy cream about 30% fat, 250 ml
- fine sea salt and freshly ground black pepper
- Preheat the oven to 200 degrees Celsius/ 400 degrees Fahrenheit.
- Cook onions: Peel and slice the onions. Heat the olive oil in a large non-stick pan and saute the onions on medium-low heat until translucent and starting to get soft, about 8 minutes. Add the thyme, sugar, and balsamic vinegar and continue cooking the onions, stirring often, until the onions start to caramelize and are soft. Remove and let cool slightly while you prepare the rest.
- Prepare sweet potatoes and cheese: Peel and slice the sweet potatoes into thin slices with the help of a mandoline. Set aside. Grate the cheese and set it aside as well.
- Line a round baking/gratin dish of approximately 26 cm/ 10 inches with the rolled puff pastry.
- Prepare pastry: Thaw it and roll it according to the packet's instructions if using frozen puff pastry. Place it in the prepared tin. Pierce the pastry with a fork all over.
- Assemble the pie: Divide the sweet potatoes into three even portions. Arrange one part of the potatoes into the baking dish, sprinkle generously with sea salt and black pepper. Cover with half of the onions and half of the grated cheese. Repeat with the second portions of sweet potatoes and the remaining onions and cheese. End with a layer of sweet potatoes.
- Whisk the eggs and cream. Season well and pour the mixture into the gratin dish.
- Bake for 50 minutes or until the sweet potatoes are cooked through. Loosely cover the pie with aluminum foil after about 30 minutes of baking time to prevent the top of the pie from getting too dark. Let the pie rest for about 10 minutes before serving.
- Gruyere is a good melting cheese. You can substitute it with another kind of good melting cheese you like. If you want this pie to be vegetarian, make sure to choose a vegetarian type of cheese.
- I use already rolled puff pastry found in the refrigerator section of the supermarket (in Germany). You can use homemade puff pastry or frozen puff pastry, which should be thawed and rolled according to the packet's instructions.