Preheat oven to 350°. Lightly grease baking sheet. In large bowl, cream butter until smooth and light. Add sugar and beat until light and fluffy, then beat in egg yolk and vanilla. Gradually add flour and mix until completely incorporated. Dough should be very firm. Shape dough into 1-inch balls and place them on prepared baking sheet, leaving 2 inches of space between them. With your thumb, make a deep indentation in center of each cookie. Bake for 7-9 minutes, or until firm. Remove baking sheet from oven and fill center of each cookie with about 1/2 teaspoon of jam, then sprinkle jam with slivered almonds. Return cookies to oven and bake for 6-8 minutes longer, or until they are light golden brown around edges. Let cookies cool on baking sheet for 2-3 minutes, then transfer them to rack to cool. Makes about 2 dozen cookies.
Let kids ?lend a hand? when you make these rich and buttery cookies. It?s perfect to use with the strawberry jam you just made! Making homemade jams and cookies are the basis for making great family memories.