Using a spoon or a piping bag, place 1 tablespoon of the poppy seed filling (about 15 grams) on the center of each round (don’t put too much filling on the shortbread round or you won’t be able to shape the hamantaschen).
The most traditional filling in hamantaschen is poppy seed so that’s the filling I use for this recipe. For the best flavor use freshly ground poppy seeds. You can grind them yourself at home using a coffee or spice grinder. Once ground, freeze the ground seeds until you’re ready to use them.
Hamantachen are triangular-shaped filled cookies that are the traditional Purim treat. The most classic filling is poppy seed, but these days you can find any flavor you can dream of inside these cookies. Powdered sugar and egg yolk make these cookies extra tender with a melt-in-your-mouth texture.
Brush the hamantaschen with the egg wash (just the dough, not the filling). Bake, rotating the trays from top to bottom halfway through baking, until the filling is bubbly and the dough is set and light golden, about 12 minutes.