½ c. butter or margarine, softened
¾ c. sugar
1 large egg yolk
2 Tblsp. whole milk
1 tsp. vanilla
1 c. all-purpose flour
½ c. unsweetened cocoa powder
¼ tsp. salt
1 large egg white, lightly beaten
1 c. chopped walnuts
15 (1-by-½-inch) plain caramels, unwrapped
3 Tblsp. heavy cream
- Preheat oven to 350°F.
- Beat together butter, sugar, egg yolk, milk and vanilla with an electric mixer until blended well. Sift in flour, cocoa and salt and beat on low speed until mixture forms a dough. Chill, wrapped in plastic wrap, until firm, at least 30 minutes.
- Roll scant tablespoons of dough into balls. Coat dough balls with egg white, letting excess drip off, and roll in nuts to coat; arrange them 1½ inches apart, on greased baking sheets and press in the center of the balls with the top of a thimble that has been dipped in cocoa, to flatten, leaving a depression.
- Bake in batches in the middle of the oven until cookies are puffed slightly but centers are still soft, 10 to 12 minutes. Remove from the oven and immediately press centers again with a thimble dipped in cocoa powder.
- Make filling while cookies are cooling. Heat caramels and cream in a small saucepan over moderately low heat, stirring occasionally, until caramel is melted and mixture is smooth. Spoon caramel into the centers of cookies and cool completely.