Carmel Nut Thumbprints

Heat oven to 325. In large bowl combine, butter, shortening and sugar. Beat until light and fluffy. Add vanilla and egg yolk; blend well. Add flour, cocoa and baking powder to butter mixture; mix well. In small bowl beat egg white until foamy; place pecans in another small bowl. Shape dough into 1 inch balls. Dip in egg white; roll in nuts. Place 2 inches apart on ungreased cookie sheets. With thumb, make indentation in center of each cookie. Bake at 325 for 12 to 14 minutes. Meanwhile in small saucepan, combine caramels and half and half; cook over medium low heat until caramels are melted, stirring occasionally. Immediately remove cookies from cookie sheet; place on wire racks. Spoon 1/2 tsp warm caramel mixture into center of each cookie. Cool completely.