Preheat oven to 350 degrees. cream butter & sugar in lg mixer bowl until light & fluffy. Beat in egg & vanilla. Add 1/2 of flour; mix well. Add remaining flour, nuts & cinnamon; mix well. Shape dough into 1" balls. Place 1" apart on unbuttered cookie sheets. Lightly press center of each ball with thumb, or the handle of a wooden spoon, leaving cup-like indention. Fill each indention w/ about 1/4 ts jam. Bake 18 min. or until lightly browned around edges. Transfer to wire racks; cool completely. ~-