Preheat oven to 350 F, line two baking sheets with parchment and set aside.

In a medium bowl, stir together the flour, baking powder, baking soda and salt; set aside.

In a large bowl, cream the butter and sugar until light and fluffy, about 3 minutes.

Add the egg and vanilla and mix again until completely combined.

Add the flour mixture to the butter mixture in 2-3 smaller additions, stirring well after each.

Roll the dough into golf ball sized balls, then roll each through the granulated sugar in a shallow bowl or large plate.

Transfer the dough to the prepared baking sheet, and use a teaspoon to make an indent in the center of each cookie.

Fill each cookie indent with strawberry jam (1-2 teaspoons) then bake in preheated oven about 15 minutes, or until cookies are golden brown.

Allow to cool before stacking.