1/4 c. packed light or dark brown sugar
1/4 c. reg. stick butter, at room temperature
1/4 c. solid vegetable shortening, at room temperature
1/2 tsp. vanilla extract
1 egg yolk
1 c. all-purpose flour
1/4 tsp. salt
1 bag Hershey kiss

Heat oven to 350 degrees. In large bowl beat sugar, butter, shortening, vanilla and egg yolk with a wooden spoon or electric mixer until blended and smooth. Add flour and salt. Stir until dough holds together. Refrigerate dough, if needed until dough is firm enough to handle. Shape into 1 inch balls. Place about 1 inch apart on ungreased cookie sheet. Press thumb deeply in center of each. Add 1 Hershey kiss, bake 10 minutes or until light brown.