Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
Combine butter, egg yolk, vanilla, and sweetener, blend for 1 minute until smooth.
Mix in almond flour until combined. Adjust sweetness to taste.
Pipe dough onto baking paper-lined sheet, leaving space for spreading. Avoid flattening too much.
Bake the cookies in the preheated oven for about 12 minutes, or until the edges turn golden brown.
Once baked, remove the cookies from the oven and allow them to cool on the baking sheet for a few minutes. They will firm up as they cool.
Carefully transfer the cooled cookies to a wire rack to cool completely. This will help them achieve a nice crunch.
Enjoy your keto butter cookies as a delicious low-carb treat!
