Combine the yeast, sugar, and 1/2 C. hot water in a small bowl. Let proof for 5-10 minutes.
In the bowl of a stand mixer, combine remaining hot water, melted butter, salt, and 3 cups of flour. Mix well.
Add mixture in bowl to yeast. Knead on speed 2 for 1 minute.
Add remaining 3 cups of flour (at the maximum, this dough will be softer and stickier than regular bread), 1/2 cup at a time, kneading between each addition. The dough should stick to the hook and pulls away from bowl. Knead with dough hook for 2 minutes.
Let rest for 7 minutes. During this time, grease a large bowl. [If using microwave for first proof, start heating 2 cups of water on high to create a warm, steamy environment].
Knead again for 3 more minutes. (Add flour if needed).
Remove from mixer and knead by hand until the dough is very satiny and smooth (approx. 1-2 minutes). Form into a tight, compact ball.
Place dough in previously greased bowl. Turn dough over so all sides have thin coating of fat. Cover with plastic wrap and set in a warm place for 1 to 1 & 1/2 hours (until doubled in size). [I put in microwave with steaming water.]
After dough is doubled in size, punch down dough. Knead 1-2 minutes on a lightly floured surface. When you poke your finger into the surface, it should give into the pressure and slowly creep back up when you remove finger.
Form into a ball. Cut in two.
Pre-heat oven to 450°. Place a small pan (for steam) in the oven to heat (below the rack bread will cook on).
Form each half into a tight loaf. You need surface tension.
Place loaves onto large baking sheet that has a tiny bit of cornmeal sprinkled across the surface. Allow to rise 30 minutes.
When dough is risen, carefully brush milk on the top of the loaves. With a sharp knife, make 3-4 shallow diagonal slashes across the top of the loaf. (This allows some steam to escape so it expands evenly during the baking process).
Slide pan into pre-heated oven. Dump 2-3 cups of ice cubes into pre-heated steam pan.
Bake 20-25 minutes (cover with foil after 10-15 minutes if needed to prevent over-browning).
Remove from oven and allow to cool.
IF USING BAKING STONE- After 1 hour into first rise, place stone in oven and start pre-heating to 450°. When ready to cook (after second rise), remove heated stone from oven. Sprinkle generously with cornmeal. Carefully transfer loaf from counter onto stone. Follow baking instructions above.