Preheat oven to 400°. Place filberts in 13 x 9 inch baking dish. Bake 8 to 10 minutes until lightly toasted. Cool nuts. Cut 12 toasted whole filberts in half, rubbing off skins if you like. Reserve halved nuts for garnish. Finely chop remaining filberts. Turn oven to 350°. In heavy 3 qt sauce pan over low heat, heat chocolate until melted and smoothe, stirring frequently. Remove saucepan from heat. With wire whisk or fork, beat in sugar, mayonnaise, vanilla and egg until well blended. Stir in flour, baking powder, and chopped filberts. Spread batter evenly in same baking pan. Bake 15 minutes or until toothpick comes out clean. Cool in pan or wire rack. When cold, cut lengthwise into 3 strips, then cut each strip crosswise into 4 pieces. Carefully remove pieces from pan. Prepare chocolate drizzle, with spoon, drizzle some in a spiral over each cookie and garnish each with a filbert half. (act 305 calories each)