Rinse the poppy seeds in a tea towel lined colander under running water; squeeze the tea towel to ring out the excess water.
Transfer poppy seeds to a sauce pan; add 3-4 cups water and bring to a simmer; simmer the poppy seeds for 40 minutes.
Drain the poppy seeds again in a tea towel lined colander; squeeze the tea towel to rinse out the excess water.
Transfer poppy seeds to a food processor (I used a Ninja) and add the sweetened condense milk; grind for 20 seconds until mixed; store in fridge while you start making the dough.
Using a zester, zest lemons until you have accumulated 3 teaspoons worth; set aside.
In a stand mixer, beat the cream cheese and sugar until fluffy; add the lemon zest, vanilla extract and salt; mix. Slowly, add the flour 1/2 cup at a time until the dough has formed.
Divide the dough into 3 balls and wrap in plastic wrap; refrigerate for one hour.
On a lightly floured surface, roll one ball into a circle (1/8" thick) as best as you can (it doesn't have to be perfect). Spread 1/3 cup of the poppy seed filling over the circle.
With a pairing knife, cut the circly into 12 wedges. Starting from the outer portion, roll up toward the center and place on a parchment lined baking sheet. Refrigerate for 30 minutes.
Preheat your oven to 350°F. In a small bowl, whisk together the egg and milk; using a pastry brush, brush each cookie with the egg mixture. Bake for 21 minutes or until lightly golden.
Transfer cookies to a cooling rack to cool completely. Sift powdered sugar over the cookies as they are cooling; then once more before storing in an airtight container.