Passover Jam Thumbprint Cookies

1 C butter 1 C sugar 1/4 tsp. salt 2 egg yolks 2 C matzoh meal, minus 2 tablespoons 2 tablespoons potato starch juice of 1 lemon grated zest of 1 lemon jam (about 1/2 C), your choice of flavors

Makes about 3 dozen Pre-heat oven to 350°F. Beat butter and sugar in bowl of electric mixer for about 10 minutes until creamy. Add eggs and beat 5 minutes more. Sift together cake meal, potato starch, and salt. Add to batter. Mix in lemon juice and peel. Form dough into 1" balls, and roll these balls in the finely chopped nuts. Place on lightly greased cookie sheets about 1 1/2 " apart. Make a small indentation in center of cookie with thumb. Bake for 15 minnutes or until lightly browned. Remove from oven and press down centers to keep indentation. Cool slightly before removing from pan. Spoon jam into center of each cookie.