How to Make It
Make Dough: Cream together butter and sugar until light and fluffy, about 5 minutes. Add eggs one at a time and mix until well incorporated, about 3 minutes. Sift in flour, baking powder, and salt. Slowly mix until well combined, 1-2 minutes. Gather dough into ball, cover with plastic wrap, and refrigerate for at least 2 hours.
Make Filling: In a medium saucepan, combine all the Filling ingredients. Heat over medium-high, stirring frequently until mixture comes to a boil. Continue stirring until mixture thickens and the bubbles become very thick and syrupy, about 10 minutes. Once thick enough (the honey should leave a clean trail along the bottom of the pan as you stir), remove from heat and set aside to cool.
Assemble Cookies: Remove dough from refrigerator one hour before rolling out.
Mash the dough on a clean surface with your hands and fold the crumbly dough into itself, almost kneading the dough. After a few minutes of recombining the dough, shape the dough into a 1 1/2-inch-thick disc. Very lightly flour your work surface and place dough on the surface. Roll dough until it’s 1/4-inch thick, pressing on the cracks that form with your fingers to create a smooth surface.
Using a 3 1/2-inch circular pastry cutter, cut out circles and use an offset spatula to unstick the circles from your work surface. Set circles aside. Reroll the scraps of dough and cut out remaining circles.
Preheat oven to 350°F. Line 2 baking sheets with parchment paper. Beat one egg in a small bowl and set aside. Place several circles on your baking sheet. In the center of each circle portion out 1 1/2 teaspoons of the filling. One at a time, brush the outside of the circle with egg wash and fold up sides and pinch edges to make a triangle. (Note: The dough will be crumbly and occasionally crack. That’s perfectly fine. Simply press the cracks with your fingers to smooth them out.) Repeat process with the rest of the circles and filling.
Brush the outsides of the cookies with remaining egg wash. Bake for 20-22 minutes, rotating halfway through by moving each baking sheet to the rack the other baking sheet was sitting on.