In a small bowl, mix yeast, water and 1 Tbsp. sugar. Allow mixture to bloom and develop a frothy layer on top in about 5 min. In a large bowl, whisk together 7 cups flour, ½ cup sugar and salt. Make a well in the center and add eggs and melted butter. Mix together with a wooden spoon, adding a little flour at a time from the sides of bowl. Stir in the yeast mixture. Mix to combine until a shaggy dough is formed. Turn out on to a lightly floured surface and knead well, about 6-8 min. If dough is sticky, work in a teaspoon of flour at a time until dough is smooth, pliable, not wet, and holds a ball shape. Divide dough evenly in half. Lightly oil two large bowls. Place one-half mixture inside each bowl and cover with plastic wrap. Let rise in a warm, draft-free place until doubled in size, about 60-90 min.

Working with one mound at a time, punch down dough and separate into 3 equal parts. Roll each piece of dough into long ropes 1-inch thick. Gather the 3 strands and squeeze them together at the top. Then snugly braid together as if you were braiding hair and squeeze bottom ends together when done to secure. Repeat with other mound of dough. Gently transfer each braid to parchment-lined baking sheets. Cover with clean dish towel and allow to rise until doubled in size and pillowy, about 1 hour.

Preheat oven to 350ºF with rack in center position. Brush both loaves with egg wash, making sure to get in the cracks and along sides of loaf. Bake for about 30-35 min., rotating baking sheets halfway through, until deep golden brown and temperature registers 190ºF in the middle.