Combine flour, sugar, baking powder and salt in a food processor and pulse to combine.
Add frozen butter and pulse a few times until butter is the size of peas.
Transfer flour/butter mixture to a bowl and stir in lemon zest.
Whisk cream, egg and yolk in a bowl and add to dry ingredients and mix until combined into a cohesive ball of dough.
Roll out into a 9x13" rectangle on a sheet of parchment.
Spread a thick layer of poppy seed filling on top.
Roll up the longer side using the parchment paper to help the rolling process ending with the seam on the bottom.
Place on a baking sheet and freeze for 2-3 hours until firm and partially frozen.
Cut dough in 3" wedges and freeze until frozen solid.
Once fully frozen you can keep them in a ziplock bag in the freezer until you are ready to bake.