Sift together flour, baking powder and salt and set aside.
In a separate bowl, cream butter and sugar with an electric mixer for 1-2 minutes.
Add egg yolks, vanilla and lemon zest.
Add flour mixture a little bit at a time until everything is incorporated.
Chill dough several hours or overnight.
Preheat oven 325 F.
Line two cookie sheets with parchment paper.
Divide dough in half.
Roll one half of dough on a floured surface to 1/4” thickness.
Use a heart shaped cookie cutter to cut hearts; use a smaller heart shaped cookie cutter to cut out a smaller heart for half of the cookies. These will be the tops.
Repeat with remaining dough.
Bake for 12-15 minutes until cookies are lightly browned.
Cool completely on a wire rack.
Once cookies are cooled, spread 1 tsp. of jam in the bottom and top with the the cut outs.
