Preheat the oven to 400°F (204°C). Line a rimmed baking sheet with parchment paper.
In a large bowl, combine the flour, sugar, baking powder, lemon zest, and salt. Toss in the butter and, using your fingers or a pastry cutter, blend everything until the butter is in pea-size crumbs. Add the fresh or frozen cranberries, dried cranberries, and white chocolate and toss to coat with the flour mixture.
In a small bowl, whisk together the cream, egg, and vanilla. Pour it into the flour mixture and stir just until everything is moistened, taking care to not overmix the dough or your scones will turn out dense rather than delicate.
Turn the dough onto a lightly floured surface and gently knead it 4 times. No more than 4 times. No less than 4 times. Do not overwork the dough.
Form the dough into a flat circle that measures 6 to 8 inches (15 to 20 cm) in diameter. Cut the dough into 8 large wedges and place them on the prepared baking sheet, leaving 1 inch (2.5 cm) between scones.
Bake the scones until they’re golden on the bottom, 16 to 18 minutes. If you're uncertain if they're done, break one open and it should have the same light and flaky consistency throughout. If it has any dense doughy spots in the center, return the pan to the oven for a couple more minutes.
Place the scones on a wire rack and let cool slightly.