In a large bowl, whisk together the flour, sugar, baking powder, and salt. Add the butter and work it into the flour mixture with a pastry blender or by pressing the pieces between your fingers until they are about the size of peas. Stir in the blueberries and lemon zest.

In a small bowl, whisk together the cream and egg. Pour over the flour mixture. Mix together with your hands or a silicone spatula just until the mixture is mostly moistened (it should still be a little crumbly).

Turn out the dough onto a lightly floured surface. Knead it gently a few times to shape it into a ball. Press the dough into an 8-inch circle. Cut into 8 wedges.

Place wedges on a small parchment or silicone-lined baking sheet and freeze for 20 minutes.

Meanwhile, preheat the oven to 400°F. Line a large baking sheet with parchment paper.

Transfer the frozen scones to the prepared baking sheet, placing them about 2 inches apart. Brush lightly with a little more cream and sprinkle with sugar.

Bake for 20 to 25 minutes or until the tops are lightly browned and the bottom edges are golden. Let cool for at least 10 minutes before serving.