Preheat your oven to 400˚F (200˚C).
Line a large baking sheet with parchment paper or lightly grease it.
In a large bowl, combine the all-purpose flour, granulated sugar, baking powder, Meyer lemon zest, and salt until well mixed.
Quickly cut in the chilled butter until blended; aim for no pieces larger than a pea.
In a separate bowl, whisk together the heavy cream, egg, lemon juice, and vanilla extract, then pour it into the dry mixture and gently stir until just combined.
Transfer the dough onto a floured surface, knead lightly, then press it into a disc about ¾ inches thick before cutting into equal slices; place on prepared baking sheet and brush tops with cream before baking until golden brown, about 12 minutes.