Preheat the oven to 350 ºF (180 ºC), then line a baking sheet with parchment paper.
Add the flour, sugar, baking powder, and salt to a large mixing bowl, then stir to combine.
Using the large holes of a box grater, grate the frozen butter directly into the bowl. Stir the grated butter into the flour mixture until evenly coated, then gently stir in the wild blueberries and white chocolate chips.
Make a well in the centre of the mixture and pour in ¾ cup plus 2 tablespoons of the cream. Add the egg directly to the cream in the well and whisk with a fork until smooth, then gently stir with the fork, drawing flour in from the sides, until a shaggy dough forms and no dry bits remain.
Turn the dough out onto a lightly floured work surface and gently pat it into an 8-inch (20 cm) circle, then slice into 8 wedges.
Transfer the wedges to the prepared baking sheet, spacing them slightly apart, then brush the tops with the remaining cream.
Bake for 23 to 25 minutes, or until the tops are lightly golden and the centres are set, then transfer the scones to a wire rack to cool slightly before serving.
Notes
For detailed ingredient notes, substitution tips, variations, and step-by-step photos, scroll through the full recipe post.
Use a digital kitchen scale for precise measurements and an oven thermometer to confirm your oven is heating correctly.
To switch to gram measurements, click "Metric grams" in the ingredients section of the recipe card.
If you notice a few stubborn dry spots of flour, add a light drizzle of cream rather than overmixing the dough.
If your kitchen is warm, chill the unbaked scones in the fridge or freezer for 10 to 15 minutes before baking to help them hold their shape.
Cut straight down when slicing the dough and avoid sawing back and forth so the edges stay clean and rise evenly.
The scones are done when the bottoms are lightly golden when gently lifted with a spatula.
Storage
Store cooled scones in an airtight container at room temperature for up to 2 days. For longer storage, freeze them in a sealed container for up to 1 month and thaw at room temperature before serving.