Heat oven to 350 degrees. Grease tart pan with removable bottom, 9x1". Beat margarine and brown sugar in large bowl. Stir in almond extract and egg. Stir in flour, baking powder and salt until well blended. Refrigerate about 30 minutes or until dough is easy to work with. Press dough on bottom and up side of tart pan. Arrange nectarine and plums on dough. Bake 30-35 minutes or until edge is golden brown. Cool 10 minutes; remove side of pan. Brush jam over top.