Place the flour and salt in a large bowl and mix well. Rub in the butter, using your fingertips. Pour the milk or water into a separate bowl then sprinkle on the yeast. Allow to foam for 5 minutes then stir into the flour to form a soft dough.
Turn the dough out onto a floured surface and knead for 5-10 minutes, until smooth. Place in a lightly oiled bowl, cover with oiled clingfilm and leave in a warm place for 1 hour to prove.
Turn out the dough onto a floured surface and knead again for about 5 minutes, until smooth. Cut off a third of the dough and shape into a ball then set aside. Shape the remaining dough into a ball and place on a greased baking tray. Top with the smaller dough ball and press down slightly.
Use a floured finger to push down through the centre of the loaf, from the top to the bottom. Cover with oiled clingfilm and leave in a warm place for 30 minutes to prove.
Preheat the oven to 220°C, fan 200°C, gas 7. Brush the loaf with a little of the egg and water mixture, sprinkle with poppy or sesame seeds, and bake for 10 minutes.Reduce the oven temperature to 200°C, fan 180°C, gas 6, and bake for 15-20 minutes. The loaf is ready when it's golden and sounds hollow when tapped on the base. Transfer to a wire rack to cool.
Cook's tip: save time kneading dough by using a food processor or hand-held mixer that has dough hook attachments.