To make the scones:
- Preheat oven to 400 degrees and line a baking sheet with parchment paper.
- Whisk together sour cream, vanilla, egg and liqueur in a small bowl. Set aside.
- Add flour, baking powder, sugar and salt to food processor. Pulse a few times to combine.
- Add butter to flour mixture in food processor and pulse until mixture resembles fine sand.
- Stir together flour mixture, wet ingredients and baking chips a large bowl until just combined. (Dough will be slightly crumbly but will come together when baked.) Turn dough out onto prepared baking sheet and gently form into an 8-inch round.
- Brush top of scone dough with heavy cream and sprinkle with coarse sugar. Use a sharp knife or dough scraper to cut round into 8 wedges. Pull scones apart slightly from one another. Bake for 20-23 minutes or until golden and baked through. Remove from pan and cool completely on rack.
To make the glaze:
- Whisk together powdered sugar, liqueur and vanilla until smooth. Drizzle evenly over scones.