Preheat waffle iron. In a medium saucepan melt the unsweetened chocolate and butter over low heat. Cool slightly. Stir in sugar, eggs, and vanilla. Add flour; stir just until combined.
Drop rounded teaspoonfuls of batter into center of each waffle grid. Bake on medium heat about 75 seconds. Using a fork transfer cookies to rack; cool. Repeat with remaining batter.
In a small saucepan combine semisweet chocolate pieces, corn syrup, and cooking oil. Cook and stir over low heat just until smooth. Cool before using. Spread over cookies; sprinkle with nuts. Makes about 24 cookies.