Preheat the oven to 375°F. Lightly grease or line baking sheets with parchment paper. In a saucepan or microwave, melt the chocolate over low heat, then let it cool. In a small bowl, mix the flour, baking powder and salt. In a medium bowl, beat the butter or margarine on low speed or by hand until smooth. Add the sugar and beat until creamy. Mix in the egg whites, vanilla and melted chocolate. Gradually add the flour mixture and stir until a stiff dough forms.

To make the spider legs, roll two pieces of dough into 8-inch lengths about 1/4 inch in diameter. Cut each roll into four 2-inch pieces. Place the pieces on the baking sheet and curve the ends to form small hooks — four curving right and four curving left. Repeat the process for each spider. Bake the legs at 375°F for 3 to 5 minutes then cool.

For the spider bodies and heads, use 1 Tbsp. of dough for each body and 1 tsp. for each head. Shape a 2-inch flat oval for the body and roll the head into a ball. Attach the head to the body flattening slightly. Press two red candies into the head for eyes and a pecan or walnut half into the back for decoration. Bake for 5 to 8 minutes. Remove from the oven and immediately insert the cooled legs into each side of the spider body while the cookies are still warm. Cool completely before serving.