To begin, combine the flour, baking powder, and salt in a bowl and stir together. Set it aside for now.
In your mixing bowl, beat the sugar and butter together until light and creamy.
Add in the eggs and vanilla extract. Beat them together.
Stir in the lemon zest.
Mix in half of the flour mixture.
Add in the milk and mix together.
Mix in the other half of the flour mixture. Mix well.
Divide the dough in half and shape into disks. Wrap them tightly in parchment paper, waxed paper, or plastic wrap. Refrigerate the dough for at least 2-3 hours or overnight.
Preheat your oven to 350 degrees.
Roll one of the disks of dough out on a lightly floured surface to 1/8 of an inch thick.
Use a biscuit cutter to cut the dough into circles.
Place a heaping teaspoon of your favorite jelly or jam in the center of each circle of dough.
Fold up three sides of the edges, pinching the corners together forming a triangular shape. (See the images in the recipe in the post above.)
Place each prepared cookie on a baking sheet that is lined with parchment paper leaving about 2 inches between the cookies.
Bake for 12-14 minutes, or until the cookies are barely golden on the corners.
Transfer the cookies to a rack to cool. Repeat with all of the dough.
Enjoy!
Notes
I have made these cookies with apricot jam, watermelon jelly, blackberry jelly, and even apple butter. You could also try them filled with Nutella!