Cut the butter into cubes and leave at room temperature to soften

Grease the baking tray and medium bowl
Fit the Dough Tool to the machine

Add sour cream into a small saucepan
Heat over a low heat for about 3 minutes until warm
Add butter into the saucepan
Stir until melted and set aside

Add flour, yeast and salt into the Mixer bowl
Attach the Mixer bowl to the machine and fit the splash guard
Mix on speed Min for about 30 seconds until combined
Transfer sour cream mixture into the Mixer bowl
Mix on speed Min for about 1 minute until combined
With the machine running, gradually add egg and egg white to the bowl
Mix on speed Min for about 5 minutes until the mixture comes together and a dough is formed
Let rest for 15 minutes
Once the dough has rested, kneed on speed Min for about 5 minutes until smooth and elastic
Transfer dough to the greased medium bowl
Cover with oiled cling film
Leave to prove in warm place for about 2 hours until doubled in size
Transfer dough to a lightly floured worksurface and gently knead a few times
Divide the dough into 3 equal pieces
Roll each piece into a 45 cm (18”) log
Braid the logs together, pinch and tuck each end underneath
Transfer dough onto the baking tray
Cover with oiled cling film
Leave to prove in a warm place for about 50 minutes until risen

Preheat the oven to 190°C
Add yolk and water to a clean small bowl
Lightly whisk together to make the glaze
Brush the dough with the egg glaze
Sprinkle the dough with poppy seeds
Bake for 35 minutes at 190°C until golden brown
Remove from the oven and let cool for 10 minutes
Turn out onto a cooling rack and let cool completely

Serve