Scoop out 8 tablespoon of lemon curd and place it on a parchement or plastic-lined baking sheet or plate, gently spread to about ¼ inch in thickness, and freeze for 1-2 hours or until solid.
Preheat the oven to 350F/180C then line a baking sheet with parchement paper then set aside.
Cream the butter, granulated sugar, and powder sugar until smooth and creamy. Add in the egg, egg yolk, lemon juice, lemon extract, and lemon zest and mix until combined.
Fold in the flour, salt, baking powder, and poppy seeds until the flour mixture disappears.
Scoop out the cookie dough, and flatten it between the palm of your hands. Place 1 tablespoon worth of frozen lemon curd in the center and gently fold the cookie dough over it. Roll the dough in between the palm of your hand, and flatten it gently to about ½ an inch in thickness.
Place the cookie dough on the prepared baking sheet and bake in the preheated oven for 12-13 minutes. Let the cookies cool down fully on the baking sheet. Don't worry if the cookies look underbaked, they will continue to bake as they cool.