Preheat oven to 350F.
Break up the almond paste into 1 inch pieces and put it in the bowl of a food processor. Add the sugar, salt, egg whites, and almond extract and process until a smooth paste forms. The dough will be wet and sticky, but you will be able to roll it into balls between your hands.
Chill the dough for 1 hour or up to 3 days.
Scoop out rounded tablespoons of dough and roll into 1 inch balls, about 25 grams each.
Press almond slices onto the sides of the cookie. The stickiness of the dough will help the nuts stick.
Place on a parchment lined baking sheet 2 inches apart and bake until the bottom edges are starting to turn golden, about 15-18 minutes. Don’t overbake.
Cool on a rack.
Optional: Dust cooled cookies with powdered sugar.
