Preheat oven to 350ºF and line a large baking sheet with parchment paper. Lightly dust a clean work surface with arrowroot flour and roll out dough to 1/4 inch thick. Use a 1 ½ inch round cookie cutter to cut out dough and place on baking sheet 2 inches apart. Top each cookie with a few almond slices by gently pressing them onto cookies and bake for 12 minutes. Roll out any leftover dough again and repeat. Cool cookies completely before dusting with powdered erythritol.