Add the ingredients to the bread machine in this order: milk, egg, butter, sugar, salt, then flour.
Scatter the yeast on top and add the lemon zest and poppy seeds with the flour.
Set the machine to the dough or brioche dough setting (not bake) and let it complete the full cycle. This usually takes about 1½ hours.
Transfer the dough to a lightly floured surface and divide it into 3 equal pieces.
Roll each piece into a rope about 30–40 cm long.
Braid the ropes loosely, as the dough will expand while rising.
Place the loaf on a lined baking tray, cover loosely with a tea towel, and leave to rise for 30–45 minutes until puffy.
Brush with egg wash for a shiny finish, or milk for a softer crust. Scatter extra poppy seeds on top if you like.
Bake in a preheated oven at 180°C (160°C fan) for 25–30 minutes, until golden brown.
Transfer to a wire rack. If you like, brush with a little lukewarm milk mixed with sugar while still warm for a soft, lightly sweet glaze.