B H & G Challah Bread

Soften yeast in warm water.
Heat milk, butter, sugar, salt and saffron until sugar dissolves. Cool to lukewarm (110*). Add 2 cups flour and eggs and beat well.
In your stand mixer fitted with a dough hook (or by hand) - combine the yeast and milk mixture and knead for 8 - 10 minutes, adding enough of the remaining flour to form a soft dough. If you are using a Kitchen Aid stand mixture you will need less flour. At any rate, do not exceed 5 cups of flour in your mixer. Shape dough into a ball.
Butter a large bowl and put dough in it, turning once to coat with butter. Cover with a damp tea towel (not terry cloth) and put into a draft free warm place such as your oven with a proofing feature and 2 cups boiling water set under the bowl. If you have a pilot light in your oven that will be warm enough. If you have no pilot just turn the oven on as low as it will go and turn it off and add the pan of boiling water. 100* is perfect proofing oven.
Let rise for 1 hour and 15 minutes or until doubled. Turn out onto a floured board and punch down, letting it rest for 10 minutes.
Divide dough into 3 even pieces and roll each piece into a rope 18" long. Place on a parchment lined (or well greased) baking sheet. Braid the strands and secure the ends, turning them under the loaf so they don't unravel. Cover with the damp tea towel and let rise another 30 minutes while you preheat the oven to 375*.
Mix egg yolk with 1 tablespoon water and brush over the braid. Sprinkle with seeds if you like, and bake for 45 - 50 minutes. If the loaf is getting too dark lay a piece of foil over the top for the last twenty minutes.
Leftovers make wonderful French Toast and Bread Pudding.