In a large bowl, sift together the flour and salt.
Warm the milk until just warm to the touch (not hot). Stir in the yeast and let sit for a few minutes until activated. Add the egg and mix well.
Make a well in the flour and add the softened butter. Slowly pour in the milk mixture.
Knead by hand or with a stand mixer until a smooth, elastic dough forms. The dough should feel soft and spring back slightly when pressed. Add a small amount of flour only if needed.
Cover the dough and let rise for about 1 hour, or until doubled in size.
Preheat oven to 380°F (193°C).
Divide the dough into two equal pieces. Roll each into a long rope about 60–70 cm (2–2½ ft).
Cross the ropes and braid, tucking the ends underneath.
Mix the egg wash ingredients and brush generously over the loaf.
Bake for 45 minutes, or until deep golden and hollow-sounding when tapped.
Cool slightly before slicing.
