These cookies are a delicious and pretty addition to your cookie trays. You can use your favorite flavors of jelly or preserves. I always use at least one red, like strawberry preserves, and one yellow, like apricot or pineapple preserves.
Heat oven to 325°. Cream butter, cream cheese and butter. Beat in egg yolk and vanilla. Add flour and mix well.
With lightly floured hands, form dough into 1" balls and place onto greased cookie sheets. Using your thumb, make an indentaion on the center of each cookie. Fill the indentation with preserves. Bake for 15 minutes or until the bottoms are lightly browned. Let cool for 3-4 minutes and then remove to racks to cool completely.