Preheat the oven to 375°F (190ºC) and line a baking sheet with parchment paper.
In a bowl, mix together Greek yogurt, egg, sweetener, vanilla extract, and a pinch of salt. Stir until smooth.
Gradually sift in almond flour and mix until a cookie dough forms. If the dough feels too sticky, add a little extra flour. Or add more Greek yogurt if it's still wet.
Gently fold in any mix-in, such as chocolate chips or fresh berries.
Scoop out 8 equal portions of dough and shape them into cookies. Place on the parchment-lined baking sheet, leaving space between them.
Bake for 10-12 minutes, or until the edges turn light golden brown. Let cool completely before serving—this helps them firm up.