These melt-in-your-mouth, buttery soft thumbprint jam cookies are made keto with whey protein powder and coconut flour, plus a colorful dollop of homemade berry chia jam.
This easy chia jam thumbprint protein cookie recipe is sugar-free, gluten-free and grain-free, plus low-carb and high protein keto with 5.3 grams of protein and just 0.8 net carbs per cookie!
Choose your thumbprint cookie flavor
Thumbprints are adorably cute and colorful cookies, so it’s no wonder that they are traditionally served on the holidays! I made this high protein cookie recipe to gift my keto friends this Christmas and they were a major hit.
But although jam thumbprints are the perfect festive cookie, they are so easy to make and to customize that they should be getting more love all year long!
The most traditional jam flavor for thumbprints is definitely raspberry. It’s said that thumbprint cookies were invented by the Swedish and they call it hallongrotta which literally means “raspberry cave”.
But traditional doesn’t necessarily mean the best: there’s nothing stopping you from using your favorite jam or preserve flavor in these cookies. Just make sure it’s sugar-free to keep them low-carb and keto friendly!
Or, you can go another route totally: here’s some different ideas of fillings for the thumbprint cookie “caves”
- Dulce de leche caramel (this is my low-carb recipe!)
- Chocolate – just add a few sugar-free chocolate chips into the cookie “thumbprints”
- Peanut butter
- Sugar-free hazelnut spread for “Nutella” style thumbprint cookies
You’ll only need the following low-carb and gluten-free ingredients to make these whey protein thumbprint cookies: (scroll down to the summarized recipe card for specific quantities)
- Unsalted butter, at room temperature (plus a pinch of salt)
- Powdered keto sweetener – it needs to be powdered as granulated won’t dissolve in the butter, and erythritol based is best (xylitol and allulose will make these cookies too soft)
- Whey protein isolate & coconut flour
- Egg yolks – at room temperature so it won’t “break” the butter
- Vanilla extract
- Sugar-free chia jam (or your choice of low-carb jam or preserve)
The ingredients for these thumbprint keto cookies are similar to my 3-ingredient shortbread butter cookies (with 4 ingredients in the whey protein version).
The main differences are that here I used coconut flour in place of almond flour and added egg yolks too, to make the dough softer and easier to shape and thumbprint.
Tips for the best keto thumbprint cookies
Use room temperature butter
This keto thumbprint cookies are buttery, super light and soft, thanks to the whipped butter and powdered sweetener.
The only way to get butter to properly incorporate air until it’s fluffy is by creaming it when it’s at room temperature.
If the butter is too warm it won’t hold air. If it’s too cold, it will be impossible to beat as it’s too hard. And you might ruin your mixer trying it!
So, simply plan ahead a little and remove the butter from the fridge about one hour before starting making the keto thumbprint cookie recipe. You can speed up the process by cutting the butter into small chunks.
You’ll know the butter is at room temperature – about 18°C (65°F) – when it feels cool to the touch. If you press on it with a finger it will make an indentation, but it won’t sink into the butter or slide around.
Get the right jam
I made these keto thumbprint cookies with my sugar-free chia berry jam recipe. This time I used mixed berries, but you can go full on any berry you like: strawberries, blueberries, currants, raspberries, etc.
You can also use your favorite flavor of any keto friendly store bought sugar-free jam for these cookies.
Be careful when selecting a sugar-free jam if you want these thumbprint cookies to remain low-carb or keto. Many labels say “no added sugars” while being full of juice concentrate (in other words, sugar).
Or, the label will say “sugar-free”, but it’s a trap: the “healthy” jam will be sweetened with maltitol, a cheap, insulin spiking, not keto sweetener.
Chill the cookie dough
While testing this recipe, the first time I baked the cookies without chilling the dough they were perfect and tasty, BUT a good amount of butter seeped out of the cookies while they were baking.
It’s not that these thumbprint cookies have so much butter in them (although they are super buttery!). The fact is, whey protein isolate and coconut flour don’t do such a good job at absorbing and keeping the butter in as wheat flour does.
To avoid butter escaping from cookies, there’s two things you can do: make sure your oven is fully preheated before baking the cookies, an chill the cookie dough.
I find more practical to chill these keto thumbprints after they are ready to bake in the cookie sheet (after shaped and filled with jam) for two reasons:
One, it’s easier to handle the dough when it’s softer (it hardens when chilled).
And two: shaping the keto cookies by hand will warm them up, which kind of defeats the purpose of chilling the dough in the first place.
But you might want to chill before shaping if you lack the space in the fridge, or if you are going to prepare just the dough ahead of time and leave the cookie shaping and baking for another day.
And that’s totally okay – the cookies will be a bit harder to shape, that’s all. Make the dough chill for a longer time so they will be colder and the butter won’t melt in your warm hands.
How to make
Start by preheating the oven to 180 °C (355 °F), and lining a baking sheet with parchment paper.
As you’ll need to chill the keto cookies before baking, you can already check if there’s enough free space in the fridge or freezer for the cookie sheet.
Cream the (room temperature!) butter with an electric mixer for about 1 full minute, then add powdered sweetener and beat until pale, light and fluffy (about 5 more minutes).
Add egg yolks and vanilla extract and beat until combined – just get all the mixture with the same color.
Then add the remaining dry ingredients for the protein butter cookies: whey protein isolate, coconut flour and a pinch of salt.
Mix everything for another minute or so, scraping the walls of the bowl to get all the powders that insist on escaping the mixers.
The ready dough will be crumbly and keep together when pressed, as shown in the pictures.
Divide dough into rounds using about 1 tablespoon of dough per cookie, and place them spaced on a baking sheet lined with parchment paper (I didn’t, but do it, it’s better!).
These cookies don’t spread at all, as it usually is the case with sugar-free and grain-free cookies. They just slightly puff up as the water content in the dough gets released in the form of steam.
So, the shape and size you give them now will be pretty much unchanged after baking.
Gently press down on the protein cookie dough balls to flatten them a bit and then make a well in the center of each one with your thumb or the back of a small measuring spoon.
I used my creatine powder spoon: the bottom is flat and not round, which created even more space for the chia jam!
Fill the thumbprint cookies with the keto chia jam, using about 1/2 teaspoon per cookie. Do overfill or it might overflow – a good reason to add parchment to the cookie sheet!
Before baking the cookies, refrigerate the baking tray for at least 30 minutes. Make it quicker by placing in the freezer for 15 minutes prior to baking.
Bake the keto thumbprint cookies in the fully preheated oven for about 10 minutes – it can be anything from 9 to 12 minutes, just keep an eye on them because they bake quickly due to the high whey protein content.
These cookies will be very soft out of the oven, and the jam filling might be runny while it’s hot. Before handling the cookies, let them cool down for at least 15 minutes.
To make the keto thumbprint cookies ahead of time, you can prepare the dough up to two days in advance – more than that and the dough will dry up.
Shape the cookies and add the “thumbprint” indentations, then wrap the whole cookie sheet in film and refrigerate.
When ready to bake them, remove the tray from the fridge and add the sugar-free jam before taking it into the oven.
Storage and freezing
Store the keto thumbprint protein cookies in an airtight container for up to 1 week – no need to refrigerate.
This recipe is suitable for freezing. The cookies will keep well for up to 3 months.
More keto & gluten-free cookies to try
Lupin flour monster cookies – These are my favorite keto cookies! They are super soft and chewy, made with peanut butter, high protein lupin flour and keto M&Ms.
3-ingredient shortbread cookies (Scottish butter biscuits) – I have the pure almond flour version, plus one with oat fiber (for a lower calorie cookie) and another with whey protein (for a high protein cookie). Guess which is my favorite? 💪
Strawberry cream sandwich cookies – These are lovely golden vanilla cookies with pink strawberry flavor filling. They are made with coconut and almond flour.
Pumpkin protein cookies – These soft puffy cookies are SO EASY to make, with pumpkin puree, coconut flour and whey protein.
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