01 - Preheat oven to 400°F. Line a baking sheet with parchment paper.
02 - In a large bowl, whisk together flour, sugar, poppy seeds, lemon zest, baking powder, baking soda, and salt.
03 - Add cold butter cubes. Using a pastry cutter or fingertips, cut butter into dry ingredients until mixture resembles coarse crumbs.
04 - In a separate bowl, whisk together cream, egg, lemon juice, and vanilla extract.
05 - Pour wet ingredients into dry mixture. Stir gently with a fork until just combined, taking care not to overmix.
06 - Turn dough onto a lightly floured surface and gently knead a few times to bring together. Pat into a 1-inch thick circle.
07 - Cut into 8 wedges and carefully transfer to the prepared baking sheet.
08 - Brush tops with a little extra cream.
09 - Bake for 16 to 18 minutes, or until golden brown and cooked through.
10 - Transfer scones to a wire rack to cool.
11 - Whisk together powdered sugar and lemon juice until smooth. Drizzle over mostly cooled scones.