Beat butter until creamy. Add sugar, salt, vanilla, and egg yolk. Beat until light. Add flour and stir well. Roll into logs about 1 inch thick. Wrap in wax paper and chill (usually overnight). Pre-heat oven to 300 F. Slice logs into cookie-sized pieces. Dip pieces into egg and chopped almond. Place on greased baking sheet. With your thumb, make an indent in the middle of each cookie and fill with jam. Bake about 20 minutes or until set.