Preheat oven to 400 degrees
Place flour, baking powder, salt and butter in a food processor and pulse until it resembles coarse crumbs. Alternatively, you can cut the butter into the dry ingredients with a pastry blender. Dump the mixture into a large bowl.
Mix 3/4 cup of the milk and 2 tbsp lemon juice together in a small bowl or measuring cup and let stand for 5 minutes.
Meanwhile, add the sugar to the dry ingredients, then stir in the lemon zest.
Make a well in the center of the dry ingredients and add the 3/4 cup of the milk mixed with the lemon juice, stir just until combined. If there are any dry spots, add the remaining milk 1 tbsp at a time until the dough has come together. You are looking for a dough that is just slightly sticky, but not wet. Then fold in the cranberries.
Turn the dough out onto a floured surface. I like to put parchment paper down first as it makes cleaning up easy.Sprinkle the top of the dough with a bit of flour, then gently press the dough into a 9-inch circle. Cut into 8 wedges with a sharp knife or pizza cutter. It is important not to handle the dough more than necessary or it will become tough. Place the wedges on a parchment-lined baking sheet with 1-inch of room between them. Whisk the egg and 2 tsp of milk together and brush over scones.
Place in the oven and bake 20 minutes or until golden brown.
Remove scones from the oven to a cooling rack.
Allow the scones to cool for about 10 minutes. Then mix the powdered sugar and 2 tbsp lemon juice. Drizzle over the scones and serve.