In a large mixing bowl, combine flour, sugar, and salt. Mix well.

In a separate bowl, dissolve yeast in warm milk and let it sit for about 5 minutes, until frothy.

Add the yeast mixture to the flour mix, along with the eggs and melted butter. Mix until a dough forms.

Knead the dough on a lightly floured surface for about 10 minutes, until smooth and elastic.

Place the dough in a greased bowl, cover with a damp cloth, and let it rise in a warm place for about 1.5 hours, or until doubled in size.

Preheat the oven to 350°F (175°C).

Punch down the dough and divide it into three equal parts. Roll each part into a long, even strand.

Braid the three strands together, tucking under the ends to secure the braid.

Place the braided loaf on a baking sheet. Cover and let it rise for another 30 minutes.

In a small bowl, mix the egg yolk and water to make the egg wash. Brush the top of the loaf with the egg wash.

Bake in the preheated oven for 30-35 minutes, or until golden brown. The loaf should sound hollow when tapped on the bottom.

Let the Zopf cool on a wire rack before slicing and serving.