Preheat oven to 400°F (200°C) and place a rack in the middle.

Line a baking sheet with parchment paper.

Lightly flour a large plate.

In a large bowl, whisk together flour, 1/4 cup sugar, baking powder, lemon zest, and salt.

Cut cold butter into the flour mixture using a pastry blender or knives until pea-sized pieces form.

Pour in 3/4 cup cream and mix with your finger until a rough, slightly sticky dough forms.

Turn the dough onto a lightly floured surface and knead until just combined.

Lightly flour a rolling pin and the work surface.

Shape the dough into a rectangle.

Roll the dough into an 8x10-inch rectangle.

Distribute frozen raspberries evenly over the bottom two-thirds of the dough.

Fold the top third of the dough over the raspberries, then fold the bottom third over that.

Gently roll the dough into a 1-inch thick rectangle.

Square the ends of the rectangle.

Cut the dough crosswise into 4 equal pieces.

Cut each piece diagonally to form 2 triangles.

Place scones on the floured plate and freeze for 5 minutes.

Transfer scones to the prepared baking sheet, spacing them 2 inches apart.

Brush with remaining cream and sprinkle with remaining sugar.

Bake for about 20 minutes, or until golden brown.

Cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely.