- 6 Tbs. (3/4 stick) unsalted butter, at room
- 1 cup confectioners' sugar
- 4 egg whites, at room temperature
- 2 tsp. vanilla extract
- 2⁄3 cup all-purpose flour
- 1⁄8 tsp. salt
For the chocolate dip:
- 3 oz. semisweet chocolate, chopped
- 1 1⁄2 tsp. unsalted butter
- 1 tsp. light corn syrup
In the bowl of an electric mixer, beat the butter on high speed until fluffy and pale yellow. Gradually add the confectioners' sugar and continue beating until well blended. Add the egg whites in four additions, beating well after each addition. Add the vanilla and beat until blended.
Over a sheet of waxed paper, sift together the flour and salt. Gradually add the flour mixture to the butter mixture and stir to combine.
Drop the batter by level tablespoonfuls onto a prepared baking sheet, spacing them about 5 inches apart and forming only 4 cookies. (The cookies must be baked in small batches because, once baked, they must be shaped quickly before they cool.) Using a lightly moistened offset spatula or the back of a spoon, spread the batter into thin ovals about 3 by 4 inches.
Bake the cookies until they are just golden at the edges, about 3 minutes. Meanwhile, prepare a second batch on the remaining sheet. Remove the baked cookies from the oven. Working quickly, use a thin, flexible metal spatula to remove 1 baked cookie at a time and wrap it lengthwise around the handle of a wooden spoon to make a hollow tube. Transfer to a wire rack to cool and repeat with the remaining 3 cookies. If the cookies become too cool to shape easily, return them to the oven for 30 seconds to soften. Continue baking and rolling the remaining batter.
To make the chocolate dip, in the top pan of a double boiler, combine the chocolate, butter and corn syrup. Set over barely simmering water in the bottom pan and stir until melted and blended. Let cool slightly. Dip about 1 inch of each cookie into the chocolate. Place on a wire rack, with the dipped end not touching the rack, until set.