1) Preheat the oven to 425°F. Line a baking sheet with parchment paper (or not; it helps with cleanup, but isn't necessary to prevent sticking).
2) Whisk together the flour, baking powder, salt, and sugar.
3) Sprinkle the vanilla over the dry ingredients, then drizzle in the cream, tossing and stirring gently all the while and adding just enough to make a cohesive dough. There shouldn't be any dry flour in the bottom of the bowl, but the dough shouldn't be particularly sticky, either.
4) Lightly flour a clean work surface. Divide the dough in half, and gently pat each half into a 5 1/2" circle about 3/4" thick.
5) Brush each circle with heavy cream, and sprinkle with coarse white sparkling sugar, if desired.
6) Place the two circles of dough on the baking sheet, and cut each into 6 wedges. Pull the wedges apart a bit, leaving them in a circular pattern with about 1" space between each wedge.
7) For best rising, place the pan of scones into the freezer for 15 minutes, while you preheat your oven to 425°F.
8) Bake the chilled scones for 14 to 15 minutes, until they're starting to brown, and they're baked all the way through, without any wet dough in the center.
9) Remove the scones from the oven. Serve warm, split and spread with a bit of sweet butter and jam or preserves.
10) Store cooled scones airtight at room temperature for several days; freeze for longer storage. To refresh, microwave individual scones very briefly; or place scones on a baking sheet, tent with aluminum foil, and reheat in a 350°F oven for 10 to 15 minutes, until heated through.
Yield: 12 scones.