Preheat oven to 275 degrees F. Cream butter with confectioners’ sugar and orange zest. Split rows of ladyfingers in half lengthwise and spread cut side with butter mixture. Place on ungreased cookie sheets, sprinkle with sliced almonds, and bake 15 to 20 minutes, or until golden brown and crisp. Cool crisps on wire racks. Store in an airtight container.