Viennese Jam Cookies
["2/3 c. butter", "1/3 c. sugar", "2 egg yolks", "1 tsp. vanilla extract", "1/2 tsp. salt", "1 1/2 c. sifted all-purpose flour", "strawberry jam"]
["Cream shortening and sugar until fluffy.", "Add egg yolks, vanilla and salt; beat well.", "Add flour gradually.", "Shape dough into balls (2 teaspoons to each ball) and place on baking sheets. Flatten slightly and use thumb to make a depression in the center of each.", "Fill these centers with 1/2 teaspoonful of jam.", "Bake in a preheated oven at 350\u00b0 for 18 minutes."]
["butter", "sugar", "egg yolks", "vanilla extract", "salt", "flour", "strawberry jam"]