Cream butter and cream cheese. Add flour and baking powder. Mix to form a dough. Chill dough for 2 to 3 hours. Mix nuts, jam, and sugar for filling.
Preheat oven to 350 degrees F. Divide dough into 4 equal parts, working with one-quarter of the dough at a time. Refrigerate remaining dough.
Roll dough very thin on lightly floured board. Cut into 2-inch squares and place on baking sheet. Put 1 teaspoon of nut filling in center of square and top with another square of dough. Press edges together with a floured fork.
Bake for 15 to 20 minutes or until lightly browned. Cool slightly and dust with confectioners’ sugar.