Preheat oven to 350 degrees and line cookie sheet with parchment paper

In one bowl whisk together flour, baking powder, and salt 

In a separate bowl use a hand mixer to cream butter and sugar until fluffy 

Add in egg and vanilla, then slowly add the dry mix 

Scoop dough onto lined cookie sheet

Press thumb in the center of the cookie (Be sure not to press too hard) and fill with jam

Bake 13-14 minutes, do not allow to brown 

Cool before serving as the jam will be very hot