Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper.

In a large bowl, whisk together the flour, sugar, baking powder, baking soda, and salt until well combined.

Add the cold cubed butter to the dry ingredients. Using a pastry cutter or two knives, cut the butter into the flour mixture until it resembles coarse crumbs with pea-sized pieces of butter still visible.

In a separate small bowl, whisk together the sour cream and egg until smooth.

Make a well in the center of the flour mixture and pour in the wet ingredients. If using vanilla or dried fruit, add them now.

Stir gently with a fork just until the dough begins to come together. Be careful not to overmix.

Turn the dough onto a lightly floured surface and gently knead 4-5 times to bring it together.

Pat the dough into a 7-inch circle about 3/4-inch thick. Using a sharp knife, cut the circle into 8 wedges.

Transfer the wedges to the prepared baking sheet, leaving about 1 inch between each scone.

For an extra golden top, brush with a little milk or cream and sprinkle with coarse sugar if desired.

Bake for 15-18 minutes until the scones are golden brown on the edges and firm to the touch.

Allow to cool for 5 minutes on the baking sheet before transferring to a wire rack.