In a bowl of an electric mixer on medium speed, beat almond butter, egg whites, and natural sweetener until thoroughly combined, about 2 minutes, scraping downsides of the bowl as necessary. Cover the bowl with plastic wrap and refrigerate at least 30 minutes.
Preheat oven to 325 degrees and line baking sheets with parchment paper.
Using a small scoop, form dough into balls (or drop by heaping teaspoons) and place 2 inches apart on prepared baking sheets.
Moisten the flat bottom of a glass with water, dip into 1/4 cup of sweetener and carefully press prepared glass bottom into dough balls, flattening dough; repeat with remaining dough.
Bake until lightly brown, 18 to 20 minutes. Remove from oven and cool cookies on baking sheets for 5 minutes, then transfer to a wire rack to cool completely.