Lemon Cheesecake Thumbprint Cookies

1. Preheat oven to 350 F.
2. Combine flour, baking soda, and salt in a small bowl.
3. In a medium bowl beat butter and cream cheese together until smooth. Add sugar and beat until light and fluffy. Add egg, yolk, lemon zest and juice, and vanilla and mix to combine.
4. Sift dry ingredients into wet ingredients and mix to combine. If dough is too soft, refrigerate until firm enough to shape into balls.
5. Combine graham cracker crumbs and salt in a small bowl. Roll 1 inch balls of dough in the crumbs to coat and place on a parchment lined baking sheet. Using a round 1/2 tsp. measuring spoon (or your thumb) make a deep indentation in center of the cookies.
6. Bake for 12 to 14 minutes, rotating sheet half way through baking. When cookies come out of the oven, use the 1/2 tsp. measuring spoon to reform the indentation (as cookies rise in the oven it will become shallower). Cool on a wire rack.
7. Heat jam in the microwave until pourable, adding a teaspoon or two of water if necessary to thin (you can also strain it to remove seeds if you desire.) Mix in balsamic vinegar.
8. Carefully spoon jam into the indentations until full. Allow jam to cool before storing or serving the cookies.