Add sugar, vanilla and salt and mix with an electric mixer until well mixed.
Mix in flour on low speed of electric mixer until well combined.
Mixture will be thick.
Refrigerate dough at least 60 minutes.
Roll dough into balls and place on greased cookie sheets.
With the bottom of a wooden spoon, make an indentation in the center of each cookie.
Spoon about 1/8 teaspoon of jam into each indentation.
Bake at 350° for about 15-20 minutes or until done.
Rotate pans half way through cooking time.
ICING:
Combine the glaze ingredients in a small bowl and whisk until smooth.
Drizzle glaze over cooled cookies.
Allow icing to set before serving.
Notes
NOTE: Preparation time does not include time necessary to chill dough.
NOTE: I use the back of a wooden spoon because it’s smaller than an actual thumb print. The larger the hole in the cookie the more the cookies spread, so it’s better to make smaller indentations.
NOTE: You cannot skip the step to chill the dough before rolling into balls and baking or cookies will not hold their shape while baking.