Attach the dough hook to mixer.
Add the sponge mixture to pre-dough, plus 3 1/2 cups all-purpose flour.
Mix until flour is fully incorporated and the dough is soft and golden. The dough will QUICKLY wrap around the dough hook and pulls away from the sides. (If you don’t have a stand mixer the batter can beat mixed by hand with a wooden spoon.) If by chance you miss where the dough pulls away from the sides and hook, it’s safe to say it happened after a few minutes and just proceed to next step.
Butter a large bowl, add the dough and turn the dough so all sides are covered with butter.
Cover bowl with plastic wrap, let rise in a warm place between 1 1/2 – 2 hours until it has doubled in volume.
After the dough is finished rising, punch the dough down, wrap in plastic and put in a plastic bag overnight or for at least 3 hours. (The plastic around the dough is to keep it from getting exposed to the air and forming a skin.)