Preheat oven to 350 F degrees, and lightly grease a cookie sheet or line with parchment paper.
Cream butter using a mixer fitted with a paddle attachment on medium speed. Add sugar and beat until smooth. Add the egg, egg yolk, and vanilla one at a time, mix until incorporated.
Combine flour, salt and ground walnuts in a separate bowl and whisk until uniform. Slowly add flour mixture to the butter. Mix until dough pulls away from the side of the bowl. Knead a few times and chill dough 1 hour.
Roll dough into 1 inch balls. Please on prepared cookie sheet 2 inches apart. Make an indentation in the center of each ball with your thumb or the handle of a wooden spoon. Fill each cookie with a generous 1/4 teaspoon of jam.
Bake until edges are golden brown, about 14-15 minutes. Remove from oven and allow cookies to rest for a minute before transferring to a rack to cool. Top with additional jam if desired.
Recipe courtesy of Stonewall Kitchen.
2 sticks unsalted butter, softened
1 cup sugar
1 egg plus 1 egg yolk, room temperature
1 teaspoon vanilla extract
2 2/3 cups unbleached all-purpose flour
3/4 teaspoon salt
1/2 cup very finely chopped walnuts
1/3 cup of one of Stonewall Kitchen’s Specialty Preserves: Stonewall Kitchen Raspberry Peach Champagne Jam, Stonewall Kitchen Wild Maine Blueberry Jam, Stonewall Kitchen Orange Cranberry Marmalade or Stonewall Kitchen Fig & Walnut Butter,/li>