Directions

1. Preheat oven to 350^°F. Mix butter, brown sugar and vanilla in mixer at medium speed until smooth. Beat in corn syrup and egg. Add 3 cups of flour and salt until blended. If dough is not firm enough to roll into balls, add an additional 1/2 cup of flour. (Dough can be made ahead of time ad refrigerated for later use. Use within 48 hours.)
2. Roll dough into 1-inch balls; roll in walnuts to coat. Place 2 inches apart on ungreased cookie sheets. Press thumb firmly in the center of each cookie to make a deep indentation. Follow instructions below for chocolate filling. Fill each cookie prior to baking.

FILLING:

1. Heat corn syrup in 1-quart microwave-safe cowl for approximately 1 minute. Add chocolate chips and stir to melt thoroughly. Using a rubber spatula, scrape into pastry bag or 1-quart plastic freezer bag. Seal tightly and snip off a tiny corner at the bottom of the bag. Squeeze filling into thumbprint holes.
2. Bake for 10 to 12 minutes or until firm. Remove to wire rack. Cool completely.