Preheat oven to 350 degrees F (175 degrees C). Grease cookie sheets.
In a large bowl, use your hands to mix together the almond paste, flour, egg whites, white sugar and confectioners' sugar until well blended. The mixture will be very sticky. Place the sliced almonds into a small bowl. Scoop out rounded teaspoonfuls of the dough and drop them into the almonds. Roll until completely coated. Place 2 inches apart onto the prepared cookie sheets.
Bake for 15 to 20 minutes in the preheated oven, until golden brown. Cool on cookie sheets for a few minutes before removing to a wire rack to cool completely.