Preheat oven to 425°F.

In a large mixing bowl, whisk together flour, sugar with lemon zest, baking powder, baking soda and salt until well blended.

Add the cold butter cubes into the dry ingredients and, using a pastry blender, cut in the butter until it forms pea-sized pieces.

In a large liquid measuring cup, whisk together the cream and yogurt and add the mixture into the dry ingredients.

Using a slotted spoon or a bowl scraper, blend the mixture until just combined. It will be quite crumbly at this stage.

Place the crumbly mixture onto a work surface.

Using a dough cutter, fold dough over onto itself until it develops into a relatively smooth dough. If the dough is still too sticky dust it with a little more flour.

Using a floured rolling pin, roll out the dough into a 12 inch square.

Fold the dough into thirds as you would fold a letter.

Fold the short sides as you would fold a letter so that you end up with a square.

Roll out the dough into a 12 inch square again dusting with flour as needed.

Gently press the frozen blueberries into the dough.

Fold the dough into thirds until a long, narrow rectangle forms.

Using a dough cutter, cut the dough into quarters. You should have 4 equal rectangles.

Cut each rectangle diagonally to form 2 triangles.

Place triangles onto 2 large parchment lined sheet pans, leaving a few inches between each one. There should be 4 scones per sheet pan.

Using a pastry brush, lightly brush some cream on the top of each scone.