Make the Sponge

1. Stir all of the ingredients together in a medium bowl until combined. Cover with plastic wrap and let sit at room temperature for at least 8 hours but no more than 24 hours. Essentially the sponge will rise and fall some.

Make the Dough

1. The next day, make the dough by combining 3 cups flour and the yeast in a Stand Mixer fitted with the dough hook.
2. With the mixer on low speed, add the water and mix until the dough comes together ~ 2 minutes.
3. Stop the mixer, cover the bowl with plastic wrap. Just wrap the plastic wrap around the top of the bowl with the dough hook in it. Don’t bother removing it.

Mix it all together

1. Let the covered bowl sit at room temperature for 20 minutes. After 20 minutes, remove the plastic wrap, add the sponge and salt, and knead the dough on medium-low speed until it is smooth and elastic ~ 8 minutes. If after 4 minutes the dough seems a bit too wet, add the remaining 1/2 cup flour, 2 tablespoon at a time, until the dough clears the sides of the bowl, but sticks to the bottom.
2. Lightly oil a large bowl, set aside. Sprinkle some flour on your counter and turn the dough out on to it. Gently knead by hand to form a smooth, round ball. Place the dough in the bowl and cover tightly with greased plastic wrap. Let rise in a warm place until doubled in size, ~60-90 minutes. Turn the dough in the bowl with a Dough Scraper. Essentially you’re folding the dough on top of itself. Cover, let rise for 30 more minutes, then repeat the turning process. Cover and let rise until the dough has doubled in size, about 30 minutes longer.
3. Sprinkle some flour on your counter and gently scrape the dough out of your bowl on the floured counter. Using a Bench Cutter, divide the dough in half. Gently pat each piece of dough into an 8 by 6″ rectangle with the 8″ side towards you.
4. Fold the bottom third of the dough up towards the center and press gently to seal. Take the top third of the dough and fold that overtop the center gently pressing down to seal. Lightly flour the side of your hand and create a large crease length-wise down the center of the dough. Starting at one end of the dough, grab the outside of the dough (on either side of the crease), pull up to the top, and pinch to secure. Repeat this for the entire length of the dough. Gently roll and set aside. Repeat the above folding, crease indention, and pinching steps for the other dough ball.
5. Spray the Baguette Pan with cooking spray and sprinkle with cornmeal. Place both baguettes in the pan. Mist the baguettes with vegetable oil spray, cover loosely with plastic wrap, and let rise in a warm place until nearly doubled in size and the dough barely springs back when poked with a knuckle, ~ 1 to 1 1/2 hours.
6. Meanwhile, adjust an oven rack to the lower third position, heat the oven to 500F. Place an empty metal pan on the bottom of the oven. Score the top of the bread with a sharp knife, cutting three-four 1/2″ deep slashes along the width of each baguette. Brush the bread with the glaze, then spray lightly with water. Place the baguette pan on the rack and immediately pour 1 cup of VERY hot water into the pan on the bottom of the oven. Shut the door fast and IMMEDIATELY reduce the oven temperature to 425F and bake until the crust is deep golden brown and the center of the bread registers 210 degrees on an instant-read thermometer, about 25 minutes, rotating the loaves halfway through baking.
7. Transfer the bread to a wire rack and let cool for about 30 minutes before serving.