Place the warm water and yeast into the bowl of a stand mixer with the dough hook attached. Stir to combine. Scrape down any yeast that sticks to the sides of the bowl. Cover with a towel and let rest for 5 minutes until mixture is foamy.
Remove towel from bowl. Add 4 cups flour, sugar, salt, and butter to the mixing bowl. Mix on low speed for 2 minutes, until flour is almost incorporated.
Add 3 cups of flour and mix for 5 to 6 minutes on low speed. Check the dough. You should have a thick, soft dough that's a little bit sticky. If the dough if pretty sticky, add another cup of flour and mix until just combined.
Grease a large bowl with a light coating of butter, oil, or non-stick cooking spray. Turn the dough into the bowl. Use your hands to roll the dough around so it's greased on all sides. Cover and let rest for 90 minutes in a warm area.
Line two baking sheets with either parchment paper or silicone mats. Set aside.
After resting, the dough should be doubled in size. Remove the towel and use your hand to punch down the dough to remove air bubbles.
Turn the dough out onto a lightly floured surface. Sprinkle more flour on top of the dough and form it so there is a uniform thickness. Use a knife or pastry cutter to portion the dough into 6 queal pieces. (You can just eyeball it.)
Form each piece of dough into a round shape and place onto one of your prepared baking sheets. Repeat with remaining dough. Each baking sheet should have 3 dough pieces with room to spread. Let the dough rest for another 20 minutes.
Preheat oven to 400 degrees F. Cut an X in the top of each dough. (This helps your bread bowls bake evenly.)
In a small bowl, beat together 1 tablespoon water and the egg. Brush egg wash over each dough piece coating the entire surface. (You can also use just the egg white.)
Bake for 30 minutes. Remove from the oven and let cool completely.
Once cooled, cut a circle in the top of each bread and remove it. Then use your hands to scoop out the bread inside, leaving some attached to the walls of your bowl. This will give the soup something to soak into without breaking through the crust. Portion your favorite soup into each bowl and serve.
Notes
You will use 7 to 9 cups of all-purpose flour for this recipe. If using bread flour, you'll need the same amount.