Preheat oven to 180°C/350°F (convection). Combine flour, baking powder, sugar, and salt in a bowl. Add soft butter and milk, then knead using a mixer with the dough hook attachment until a dough forms. Add yogurt. The dough will become sticky. Now continue to knead with your hands. If you like cranberries, add them now. With your hands, spread out the dough to approx. 2 cm-/0.75 in.-thick on a floured surface.
Use a cup to cut out circles and place them on a baking sheet lined with parchment paper.
Brush egg yolk (whisked with some water) on the scones, if preferred. I don’t normally do that, so that the scones come out lighter. Bake at 180°C/350°F (convection) for approx. 20 - 25 min.