Instructions for making the scones:Preheat oven to 375º.
In the bowl of a food processor, combine the flour, sugar, baking powder, lemon zest, poppy seeds, and salt.
Pulse a few times until everything is well combined.
Add in the cold, cubed, butter and pulse again until the butter is just incorporated and the mixture looks sandy.
Add the lemon juice to the flour mixture.
Whisk the egg, cream, and vanilla together in a small bowl or measuring cup and add to the flour mixture in the food processor.
Turn on the food processor and process until the ingredients are just mixed and a dough ball has formed around the blade. It takes about 30 seconds
On a lightly floured work surface (or a piece of parchment paper), gently flatten the ball of dough into a disc, about 3/4" thick.
Cut into eight even triangles (like cutting a pizza).
Place the scone triangles on a sheet pan lined with parchment paper and bake at 375º for 10-12 minutes. The scones are done when the tops are puffed and cracked and the bottom edges are just barely starting to brown.
Let cool and coat with Lemon Icing.
To Make the Lemon Icing:Combine the powdered sugar, lemon juice, lemon zest, and salt in a small bowl. Stir together until smooth. The mixture should be thick but still pour off a spoon. Add more lemon juice if the icing is too thick.
Drizzle the icing over the scones and allow to set.
Notes
Add the lemon juice to the flour mixture instead of the wet ingredients. This will prevent the cream from curdling!