4 ounces bittersweet chocolate, chopped medium fine
1 1/2 teaspoons light corn syrup
Vegetable-oil cooking spray
In a mixing bowl, combine sugar, flour, and salt; make a well in the center. Add melted butter, egg whites, cream, and vanilla. Mix until well combined. Refrigerate, covered, for at least 2 hours or overnight.
Heat oven to 425 degrees. Place rack in center. Spray two baking sheets (do not use air-cushioned sheets or line with parchment) with vegetable-oil spray. Spoon a heaping tablespoon of batter onto baking sheet. Using the back of a spoon, spread batter into a very thin 6-by-3 1/2-inch oval. Repeat, making three more ovals of batter on the sheet.
Bake just until brown around edges, about 6 minutes. Meanwhile, prepare second baking sheet. Working quickly, use a knife or long metal spatula to transfer a cookie to a work surface; roll around a chopstick or thin wooden dowel, forming a cigarette shape; place on wire rack to cool. Repeat with remaining 3 cookies. If they get too stiff, return baking sheet to oven for 30 seconds. Continue baking and shaping cookies until batter is used up.
Combine chocolate, corn syrup, and remaining 4 tablespoons butter in a double boiler over simmering water; stir occasionally with a rubber spatula until smooth. Let cool slightly. Dip about 1 inch of each cooled cookie into chocolate. Place on a wire rack, with dipped section off the edge, to dry.
Store between waxed paper in an airtight container for 2 to 3 days.
To make this recipe as seen on "Martha Bakes," combine chocolate and 2 teaspoons vegetable oil in a double boiler over simmering water; stir occasionally with a rubber spatula until smooth. Let cool slightly. Dip about 2 inches of each cooled cookie into chocolate. Roll dipped edge in finely chopped toasted nuts, if desired. Place on a wire rack, with dipped section off the edge, to dry.