Preheat the oven to 425°(F). Line a large baking sheet with parchment paper and set aside.
In a large bowl, combine flour, baking powder, brown sugar, cinnamon, salt, and nutmeg, mix well to combine.
Cut the butter into small cubes, then, using a pastry cutter, work the butter into the dough until it resembles a coarse meal. The chunks of butter should be about the size of peas.
In a glass measuring cup whisk together the heavy cream, egg yolks, vanilla, and maple extract (if using).
Pour the liquid mixture into the center of the flour mixture. Then add in the walnuts and cranberries. Use a spatula to stir everything together until just moistened. Don't worry if the dough looks dry/shaggy!
Empty the loose dough out onto a clean, lightly floured work surface. Knead the dough, dusting your hands/the dough with more flour if needed, until it comes together, then shape it into an 8-inch disc.
Cut the disc into 8 even wedges and carefully transfer them to the prepared sheet, placing them 2-inches apart. Place in the refrigerator for 15 to 30 minutes.
Remove the tray from the refrigerator and lightly brush each scone with egg wash. Sprinkle generously with the sparkling sugar. if using.
Bake for 20 to 22 minutes, or until golden brown. Allow scones to cool for 10 minutes on the baking sheet, then drizzle with the glaze and serve warm!
For the Egg Wash:
In a small bowl, whisk together the egg and water until well combined.
For the Maple Glaze:
In a small bowl combine the confectioners' sugar, maple syrup, and milk and whisk until well combined. If the glaze appears too thin, add a small amount of confectioners’ sugar. It should be thick but pourable.