Preheat the oven to 350F or 175C and line two baking sheets with parchment paper.
Dust some flour on your workspace and roll out one disc of dough at a time until it's between 1/3 and 1/2-centimeter thick. Add more flour as necessary to prevent sticking.
Cut out 3” or 7.5cm circles (I use the rim of my whiskey glass), re-rolling scraps as needed. Brush the edges with egg wash. Scoop 1 teaspoon of graham cracker crust and pack it into your spoon. This will help it stick together. Then plop it in the center of your hamantaschen and flatten slightly with the back of your teaspoon. Top that with 1/2 teaspoon of cream cheese. At this point, you can optionally add your cherry on top or save it for the end. If adding it now, be sure to press it slightly into the center. It might fall to the side while baking if it's left gently on top.
Fold the edges up to form a triangle shape, pinching the corners firmly to seal. Then brush the edges with egg wash.
Place on the baking sheets, 1 inch or 2.5 centimeters apart. Bake until the dough is lightly browned, about 17 minutes.
If you haven't already, top each hamantaschen with a canned cherry and press it gently into the center of the cream cheese. Let cool for about five minutes before transferring to a cooling rack. After another five minutes, you can dive in!