In a large mixing bowl, whisk together the flour, yeast, and salt.

Add the butter and mix with your hands until the mixture resembles coarse crumbs.

In a separate bowl, whisk together the milk and egg yolk.

Add the milk mixture to the flour mixture and stir until a dough forms.

Turn the dough out onto a floured surface and knead for 5-7 minutes until smooth and elastic.

Place the dough in a greased bowl, cover with a clean towel, and let it rise in a warm place for 1 hour.

Preheat the oven to 350°F (180°C).

In a small mixing bowl, mix together the feta cheese, sour cream, egg, and parsley.

Roll the dough out on a floured surface to 1/4 inch thickness.

Cut the dough into triangles and spoon the filling onto the wide end of each triangle.

Roll the dough up, starting from the wide end, and shape into crescents.

Place the crescents on a baking sheet lined with parchment paper and let them rest for 10 minutes.

Bake for 20-25 minutes, until golden brown.

Serve warm and enjoy!