In a large bowl, cream softened butter and sugar together in a bowl until smooth and creamy. Stir in almond extract.
Stir flour into butter mixture 1 cup at a time and mix in salt.
For walnut cookies:
Beat egg whites in a separate bowl; transfer walnuts to a shallow bowl. Pinch off and roll dough into 1-inch balls, dip each in beaten egg white, and roll in walnuts. Place cookies on a lined or coated baking sheet. Use your thumb to form an indention into the top of each cookie and spoon a small amount of jam into the hollow.
Bake cookies in the preheated oven until very lightly browned, 11 to 14 minutes.
For glazed cookies:
Pinch off and roll dough into 1-inch balls. Place cookies on a lined or coated baking sheet. Use your thumb to form an indention into the top of each cookie and spoon a small amount of jam into the hollow.
Bake cookies in the preheated oven until very lightly browned, 11 to 14 minutes.
For the glaze: In a small bowl, combine confectioners' sugar, extract and milk until you have a somewhat stiff and thick icing. (Add more milk or more sugar until satisfied.) Dip spoon into icing and drizzle over cookies. Leave the glaze to set for a couple of hours.
Recipe by CHIC AND SUGAR at https://www.chicandsugar.com/2014/11/holiday-cookie-2-thumbprint-cookies/