In a large mixing bowl, combine the lukewarm water and a pinch of sugar. Sprinkle the two packages of active dry yeast over the top and let it sit for about 10 minutes, or until it becomes frothy.
Once the yeast is frothy, add the sugar, sliced unsalted butter, warm milk, honey, salt, and 4 eggs to the bowl. Mix with a whisk until well combined. Gradually add the bread flour, starting with about 4 cups, and mix until a shaggy dough forms.
Transfer the dough to a floured surface and knead for about 8-10 minutes, adding more flour as needed, until the dough is smooth and elastic.
Place the dough in a lightly greased bowl, cover it with plastic wrap, and let it rise in a warm place until it has doubled in size, about 1 to 1.5 hours.
Once risen, punch down the dough to release any air bubbles. Divide the dough into three equal pieces for braiding. Roll each piece into long ropes, approximately 12-15 inches long.
Lay the three ropes side by side on a baking sheet lined with parchment paper. Pinch the tops together and braid the ropes down to the end. Once finished, pinch the ends to seal and tuck them under the loaf.
Cover the braided loaf with plastic wrap and let it rise again for about 30-45 minutes, until puffy.
Preheat your oven to 350°F (175°C). In a small bowl, mix the beaten egg, egg yolk, and water for the glaze. Gently brush the mixture over the loaf, being careful not to deflate it. If desired, sprinkle sesame or poppy seeds on top for added flavor and texture.
Bake the loaf in the preheated oven for 30-35 minutes, or until the top is golden brown and the bread sounds hollow when tapped on the bottom.
Allow the bread to cool on a wire rack for at least 20 minutes before slicing.
