Pre-heat the oven to 350˚F. Line one large baking sheet with parchment paper or silicone baking mat. Set aside.
In the bowl of a standard electric mixer fitted with the whisk attachment, beat the butter, the sweetener and vanilla extract at medium speed until it becomes fluffy and well combined.
Add ½ cup of almond flour at a time. Notice that the dough will be a little crumby, but it will stick when pressed together.
After adding all the almond flour and everything is well combined, scoop about 1 tablespoon of the dough and shape it into balls. Make an indentation with your thumb into each ball. Probably the dough will crack a little when you press your thumb into it. You just have to re-seal some cracks by simply smooth it out with your fingers. But know that it’s totally fine to have a few cracks.
Bake for about 12-14 minutes or until they get golden brown. The cookies will be very fragile when you remove from the oven. So, allow them to cool down for about 10 minutes before handling them.
Fill each cookie with a 1/2 teaspoon of homemade sugar-free nutella. Enjoy!