Preheat the oven to 400 degrees F.
Prepare the scones: In a large bowl, stir together the flour, powdered sugar, baking powder, and salt.
Pour in the heavy cream, vanilla extract, and cranberries. Stir until just combined. (The dough will still be a bit sticky.)
Lightly flour your working surface, and sprinkle it with the slivered almonds.
Pour the dough out on the floured surface, and sprinkle a little extra flour on top. Divide the into two equal sections. Pat each section into a disc, pressing on the slivered almonds underneath as you do, until you have two discs each about 6 inches wide and 1 inch thick.
Flip each disc and ensure the top is covered in almonds (feel free to press on a few extras by hand if needed). Cut each disc into six wedges.
Place the cut scones on a baking sheet. Bake at 400 degrees for 15 minutes, or until the edges just start to turn golden brown.
Let the scones cool completely. Meanwhile, prepare the glaze – combine the powdered sugar, milk (or cream), and vanilla in a small bowl. Stir until well combined.
When scones are cool, drizzle the glaze on top. Let sit for a few minutes, then enjoy!