In a large mixer bowl beat margarine or butter and sugar with electric mixer on medium speed till fluffy. Add bourbon; beat well. Gradually add flour and cocoa powder, beating till well mixed. Stir in chocolate pieces. Chill 2 hours or till firm enough to handle. Shape dough into 3 cm balls. Roll in egg white, then in nuts. Place on a lightly greased baking sheed. Bake in a 180ºC oven about dozen minutes or till edges are firm (The center will still be soft). Cool on bakin sheet for 1 minute. Finish cooling on wire racks. Makes about 30