Preheat your oven to 375°F. Line two baking sheets with parchment paper.

In a medium bowl, combine the dry ingredients- flour and salt and set it aside.

In a large bowl, use an electric mixer to cream the butter and brown sugar until creamy, about 2 minutes.

Separate the eggs and place the egg whites in a small bowl; gently beat them. You will be using this egg wash to dip your cookie dough balls in.

Add the egg yolks to the butter mixture and mix well. Stir in the vanilla extract.

Gradually add the flour mixture to the butter mixture and mix until the cookie dough pulls alway from the sides of the bowl and a soft dough forms. 

Cover the bowl with plastic wrap and chill the dough in the refrigerator for 30 minutes.

Pour the coconut flakes in a small bowl. Roll the cookie dough into 1-inch balls. Dip each ball in the egg wash, then roll them in the coconut flakes to coat well.

Place the cookie balls on the prepared baking sheet and use your thumb or the end of a wooden spoon handle to press indentations into the center of each cookie. Fill each indent with jam using a small measuring spoon or a piping bag.

Bake the cookies for 14 to 16 minutes or until they are golden brown. Let them cool on the baking sheets for a few minutes before transferring them to a wire rack to cool completely.