Directions

1. Heat oven to 350 degrees. In the bowl of an electric mixer fitted with the paddle attachment, beat together 1 stick butter, sugar, salt, and vanilla on medium-high speed until smooth, about 2 minutes. Beat in flour, beginning on low speed and increasing to medium high.
2. Roll dough by teaspoonfuls into balls, and place 1 inch apart on an ungreased baking sheet. Bake for 10 minutes, remove from oven, and press thumb into tops of cookies to make indentations. Return to oven, and bake until light brown on the edges, 7 to 9 minutes more. Remove to a wire rack to cool.
3. Combine chocolate, 4 tablespoons butter, and corn syrup in a small heat-proof bowl. Set over a pot of simmering water; stir occasionally until melted and smooth. Allow to cool slightly. When cookies are cool, fill the thumbprints with the chocolate mixture.