12 tablespoons (1 1/2 sticks) cold unsalted butter, cut into small pieces
1 1/2 cups cold buttermilk
1/2 cup heavy cream
a 3-inch round cutter
Preheat the oven to 450 degrees F. Line a baking sheet with parchment paper.
Combine the flour, baking powder, baking soda and salt in a large bowl. Cut in the butter using your fingers or a pastry cutter until the mixture resembles coarse meal. Add the buttermilk and gently mix until a dough just begins to come together.
Scrape the dough onto a lightly floured counter and pat into a 10-by-12-by-1-inch rectangle. Use a 3-inch round cutter to cut out biscuits. Reroll the scraps and cut again.
Put the biscuits on the prepared baking sheet, leaving a few inches between them, and brush the tops with cream. Bake until lightly golden brown, 12 to 15 minutes. Serve hot.