Thumbprint cookies

Source:joyof baking
Ingredients:
All purpose flour    - 1 cup
Unsalted butter      - 1/2 cup,room temperature
Granulated sugar   - 1/4 cup
Egg                       - 1 large .separated
Pure vanilla extract- 1/2 tsp
Salt                       - 1/8 tsp
Almonds               - 3/4 cup chopped
Strawberry jam     - 1/2 cup

Method:
Combine all purpose flour and salt in a small bowl.Beat butter,egg yolk,sugar  and vanilla extract  in a  large bowl with an electric mixer at medium speed  until well combined.Add flour mixture to this  and combine well.Press mixtures together to form a ball. Cover with a plastic wrap and refrigerate this dough  for 30 minutes.
Preheat oven to 350 degree F.Adjust the rack to middle position.Coat cookie sheet lightly with non stick cooking spray.
Beat egg white in a shallow bowl until foamy.Place almonds chopped in another plate.Measure about 2 tsps dough for each cookie.Roll it between your arms to form balls.Dip each dough balls onto egg whites and then roll into almonds.Pressing down with your thumb, make indentation into the center of each cookie  and fill with about 1/4 -1/2 tsp of jam.
Place on the cookie sheets and bake for about 13-15 minutes until cookies are set.Remove from oven.Cool on baking sheet for 2 minutes.Remove to wire rack to cool completely.