Preheat oven to 350 degrees F. Line cookie sheets with silicone baking mats or aluminum foil to prevent cookies from sticking.
In a large bowl, mix butter until creamy. Either use your electric mixer or beat by hand. Gradually add sugar; beating until light and fluffy.
Stir in almond extract. Gradually add flour to mixture, beating well after each addition.
Roll dough into 1-inch balls. Place each ball 1-inch apart on prepared baking sheets.
Use your thumb to make indentation into center of each cookie ball. Edges may slightly crack - you can leave as is or push the edges back together.
Fill each indentation with 1/4 teaspoon of your favorite jam.
Bake cookies for 10 to 12 minutes or until edges are lightly browned. Remove from oven and let cool on the baking sheet before moving cookies to wire rack to completely cool. Cookies may crumble if you move them while still hot.
When cookies have cooled, drizzle tops with Milk Frosting recipe below.
In a small bowl, combine powdered sugar, almond extract, and enough milk to make frosting a thin consistency and easy to drizzle.
* You must use butter in this recipe. The secret of a great shortbread cookie is butter or it just will not taste like shortbread!
** Can use any fruit jam you prefer.
Thumbprint Cookies Recipe: https://whatscookingamerica.net/Cookie/ThumbPrint-Cookies.htm