In a large mixing bowl, whisk together the flour, sugar, salt, and baking powder until well combined.
Using a box grater, grate the frozen butter into the dry ingredients. Toss to coat, then cut in using forks or a pastry cutter until crumbly. Chill mixture.
In a separate bowl, whisk together the cream or buttermilk, egg, and vanilla until smooth.
Pour wet mixture over chilled dry mixture. Add chosen add-ins and gently fold to combine until just moistened.
Turn dough onto a floured surface. Shape into an 8-inch circle and cut into 8 wedges, or two 5-inch discs for smaller scones.
Alternatively, scoop dough directly onto a lined baking sheet using ¼ cup per scone for drop scones.
Brush tops with remaining cream and sprinkle with coarse sugar. Chill shaped scones for 15 minutes.
Preheat oven to 400°F (204°C) while scones chill.
Line a baking sheet with parchment. Bake scones for 18–26 minutes until golden and crisp on edges.
Let cool slightly before serving. Add optional toppings like glaze or jam if desired.