Heat oven to 400ºF. In a food processor, combine flour, sugar, baking powder, baking soda, salt, and cranberries. Pulse until combined. Add butter and pulse to a mostly sandy texture with some clumps of butter. Do not overmix. Add lemon zest and juice, buttermilk, and heavy cream and pulse several times, until combined. Line sheet pan with parchment paper. With an ice cream scoop, scoop dough into 12 to 16 portions onto sheet pan. Rest dough in freezer at least 1 hour, until frozen. Bake 25 to 30 minutes, until golden brown. (Do not thaw before baking.) In a small bowl, combine milk and powdered sugar to make a glaze. Pour glaze over scones while still hot.