To bake this European Kolacky, beat butter, cream cheese, milk, and sugar in medium-size bowl with electric mixer until thoroughly blended. Beat in egg yolk. Sift flour and baking powder and stir into butter mixture to make stiff dough. Cover bowl and refrigerate several hours or overnight. Preheat oven to 400° F. Roll out dough on lightly floured surface 1/4-inch thickness. Cut dough with floured 2-inch cookie cutter. Place cookies on ungreased baking sheets about 1 inch apart. Make impressions in center of cookies with thumb or back of spoon. Spoon 1 teaspoon fruit filling into center of cookies. Bake 10 to 12 minutes or until ligthly browned. Remove from baking sheets and cool completely on wire racks. Sprinkle with confectioners sugar just before serving.