Apple & Caramelized Onion Tartlets – Low Carb and Gluten-Free


Sweet apples and caramelized onions in a low carb, gluten-free pastry crust. A delicious savory appetizer. This post is sponsored by Kitchen PLAY and Opal Apples.

Low Carb Apple and Caramelized Onion Tarts

Apples have long been one of my favorite foods, and I truly believe that there is nothing more satisfying than biting into a crisp, juicy apple. I can’t eat them to excess like I used to do, but I still find ways to include them in my healthy low carb, gluten-free diet. I often eat one before going for a run or working out, and I dearly love to incorporate them in my baking. I am also fascinated by the discovery or creation of new varietals, the crossbreeding of this or that kind to achieve a particular appearance, a specific flavour or another desirable trait. I’ve tried a great many kinds of apples in my day, but only recently have I been introduced to the Opal apple.

The Opal is a beautiful apple indeed. It’s round and bright golden yellow, much brighter than Golden Delicious. It’s also shatteringly crisp, a trait I love in apples. The flavor is distinctive and quite sweet, and one of its biggest selling points is the fact that it doesn’t brown when cut. It just naturally resists oxidation. The Opal is also an apple that gives back, by donating a portion of proceeds to youth-based programs that focus on food security and politics, nutrition or agriculture.  This year, Opal’s Youth Make a Difference initiative will be awarding $75,000 to youth-based projects serving communities in the U.S. where youth take leadership roles.  The grant application process ends February 28. That’s quite a lot of ask of an apple, so I confess I am impressed.

Apple & Caramelized Onion Pinwheels Low Carb Gluten-free

As part of a Kitchen PLAY progressive party, I was asked to create an appetizer using Opal apples. I considered many possibilities, including using thinly sliced Opals as the “cracker” for cheese and other savory toppings. In the end, I settled on playing up its sweet flavor in combination with caramelized onions and shredded fontina cheese. I’ve recently developed some wonderful low carb, gluten-free pastry and I find myself wanting to see if it will hold up against a variety of fillings. Little bite-sized savory tarts with a tangy, slightly sweet apple filling sounded just right. Similar recipes often include a little sugar to enhance the apple flavor, but Opals are sweet enough and need no enhancement.

These little tarts make a truly delicious appetizer. You can also have some fun with the shape of the tarts and create little pinwheels. As a diehard apple connoisseur, I sincerely recommend trying Opal apples if you come across them. From December to April, a limited supply will be available nationwide in select grocery stores, including Costco. You won’t be disappointed – their flavor and appearance sets them apart.

Apple and Caramelized Onion Tartw with Low Carb Gluten-Free Almond Flour Pastry

Want to know more about Opal Apples?

The Opal® apple, also known as UEB 32642 variety apple, is non-GMO and was first discovered in Europe in 1999. In March 2010, Opal was first made available in the United States, and is grown exclusively at Broetje Orchards located along the Snake River in Prescott, WA. Opal is distributed by FirstFruits Marketing of North America, a collaborative apple marketing company owned by growers who share a commitment to producing high quality fruit while balancing the demands of purpose, people, planet and profit so that a portion of profits can be donated to non-profit missions supporting the underserved. For more information on where to buy Opal® Apples, visit their website at and like them on Facebook at

And check out all of the other delicious Opal Apple recipes on Kitchen PLAY.

Join us for an #OpalApples Twitter Party where you could win one of five prize packs, including a shipment of these tasty apples. For more information, guidelines, and to register for a chance to win, visit Then join in on January 21, 2014 at 9:00 PM ET (6:00 PM PT), using hashtag #OpalApples. Here’s a clue to help you win: Opal apples are available from December through April.

Low Carb Savory Tarts with Apples and Caramelized Onions

Disclosure: I was compensated for this post by Kitchen PLAY and Opal Apples. As always, all opinions, thoughts, recipes, photography, random tangents and incoherent ramblings are my own.

Apple & Caramelized Onion Tartlets – Low Carb and Gluten-Free

Yield: 24 mini tartlets

Serving Size: 2 tartlets

Sweet apples and caramelized onions in a low carb, gluten-free pastry crust. A delicious savory appetizer for any occasion.


  • 3 tbsp butter, divided
  • 1 medium onion, finely chopped
  • 1/2 tsp kosher salt
  • 2 Opal apples, finely chopped
  • 2 ounces fontina or fontal cheese, grated
  • 1/4 tsp dried thyme
  • 1/8 tsp coarsely ground pepper
  • Sprinkle dried parsley
  • Pastry:
  • 1 1/4 cup almond flour
  • 2 tbsp coconut flour
  • 2 tbsp arrowroot starch
  • 1 tbsp Swerve Sweetener
  • 1 tsp xanthan gum
  • 1/4 tsp salt
  • 5 tbsp butter, chilled and cut into small pieces
  • 2-4 tbsp ice water


  1. For the filling, heat 2 tbsp butter in a large skillet over medium-low heat. Once melted, add onions and salt. Cook, stirring frequently, until onions are soft and golden brown, about 20 minutes. Transfer onions to a large bowl and set aside.
  2. Add remaining tbsp butter to skillet and increase heat to medium. Add chopped apples and cook until soft and fragrant, about 10 minutes. Transfer to bowl with onions.
  3. Add cheese, thyme and pepper to another bowl and stir to combine. Season to taste with additional salt and pepper.
  4. Preheat oven to 325F.
  5. For the pastry, combine almond flour, coconut flour, arrowroot starch, sweetener, xanthan gum and salt in the bowl of a food processor. Pulse to combine.
  6. Sprinkle surface with butter pieces and pulse until mixture resembles coarse crumbs.
  7. With processor running on low, add ice water, one tablespoon at time until dough begins to clump together.
  8. Place a large piece of parchment on work surface and dust liberally with additional almond flour. Turn out dough and pat into a rough rectangle. Sprinkle with more almond flour and cover with another large piece of parchment.
  9. Roll out to a large rectangle at least 12 by 8 inches (you should be able to get it larger than this without rolling too thinly), remove top parchment and cut into 2 inch squares. Carefully lift squares from bottom parchment with a sharp knife or offset spatula and place in cavities of a mini muffin tin.
  10. Fill each with one heaping tablespoon of filling. Bake 22 to 25 minutes, until pastry edges are golden. Remove from oven and let cool at least 10 minutes in pan.
  11. Alternatively, you can roll pastry out to 12 by 9 inches and cut 3 inch squares, then cut from each corner one inch toward the center. Place 1 tbsp of filling in center of square and fold every other point (one from each corner) in to the center. This will create a pinwheel pattern. Place on a parchment lined baking sheet and bake 22 to 25 minutes.


Makes 24 mini tartlets or 12 pinwheels.

Serves 12. Each serving has 10 g of carbs and 3 g of fiber. Total NET CARBS = 7 g.

Per serving: 186 Calories; 15g Fat (71.2% calories from fat); 4g Protein; 10g Carbohydrate; 3g Dietary Fiber; 26mg Cholesterol; 246mg Sodium

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  1. Kathy says

    Carolyn, would you have the nutritional analysis for the pastry alone? I am thinking that the pastry shells could be made and frozen, and then used for a variety of savoury fillings. With company coming in two weeks, I would love to have a batch of these made ahead and ready, and since I know how well the mincemeat tart pastry turned out, I am sure this will too. Would you please comment if you think that this pastry would lend itself to a quiche recipe? Thanks if you can provide the numbers (and thanks anyway, even if you can’t!)

    • Carolyn says

      Sure let me work out those numbers. Yes, it would be great as quiche, but it is fragile and hard to get into a pie pan in one piece (patches back together very nicely, though!). I would blind bake it for 10-12 min first and then cover the crust edges with foil while the quiche bakes. Make sure to prick the pastry at the bottom of the pan too!

    • Carolyn says

      Hi Kathy – here are the pastry numbers. First I am going to give you the raw counts for the eentire batch of pastry because it will vary depending on what you make and how many servings it has.

      1499 Calories; 132g Fat (75.0% calories from fat); 36g Protein; 63g Carbohydrate; 28g Dietary Fiber; 155mg Cholesterol; 1202mg Sodium.

      Assuming 10 servings per whatever recipe you are making, here are the counts per serving: 150 Calories; 13g Fat (75.0% calories from fat); 4g Protein; 6g Carbohydrate; 3g Dietary Fiber; 16mg Cholesterol; 120mg Sodium

      • Kathy says

        This is so good of you to go to all this extra trouble, and I thank you. I am delighted that you gave the calculations for the whole batch of pastry because (and I am embarrassed to say) in my family we are more inclined to divide a pie into 8 slices rather than 10. Even with our piggy serving size, the calculations per serving are still very reasonable I think, and I am confident that this pastry will be added to my growing list of your recipes that have become our favourites.

          • Heather from Canada says

            Hi Carolyn, is this the pastry from the mincemeat tarts? Did you leave out the 2 tbsp of Bob’s Red Mill gluten free flour on purpose? I made chicken pot pies with this pastry (from the mincemeat page) and they were amazing by the way (just omitted the Swerve as I prefer a very plain pastry for that). SO HAPPY to have pastry in my life again!!

          • Carolyn says

            This one is a little different. I’ve been playing around with different ingredients, and this one was actually originally meant for cheese straws but they wouldn’t hold together. So I used it for tarts. They’re both good recipes, and I just like experimenting!


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