A loaded sourdough loaf stuffed with all the flavors of your favorite French Onion soup. It is filled with caramelized onions, fresh thyme and melty gruyere cheese.
Add butter to dutch oven. Once hot and melted, add the onions, salt and pepper, and allow them to cook down and deeply caramelize for about 20 to 25 minutes, stirring frequently, until the onions become very dark, soft and jammy.
Add in the garlic, wine, Worcestershire, and balsamic vinegar, and allow it to bubble up and reduce for about 30 seconds. Allow mixture to simmer until reduced.
Place into refrigerator to cool.
Prepare Bread
In a large bowl combine water, starter, salt and flour. Mix until most of the flour has been combined. Cover and let sit for 30 minutes.
Cover and let ferment for 8-10 hours. I like to mix this up in the morning and let it sit during the day so I can keep an eye on the dough. You can perform stretch and folds if you desire, but I usually don't.
After the dough has doubled in size pour onto the counter and gently stretch into a rectangle. Spread 1/2 of the caramelized onions, 1 tsp fresh thyme, and 1/2 cup shredded gruyere. Fold dough into thirds and top with 1/4 of the caramelized onions, 1 tsp fresh thyme and 1/4 cup shredded gruyere.
Fold dough into thirds again and flip the dough over and shape using a push and pull motion. Do this gently, you do not want the surface to tear, but want the folds no longer visible. The dough will be more prone to ripping with the inclusions.
Alternatively, you can place the dough into a standard loaf pan if shaping is intimidating or your dough rips.
Sprinkle the loaf with flour and place into a small bowl (or banneton basket). Cover and let proof for 30-90 minutes on the counter. While the dough is on its final proof preheat a dutch oven inside your oven at 450. You want the Dutch oven nice and hot!
After your dough has proofed, flip onto a piece of parchment paper and score the loaf.
Gently place your parchment lined loaf into your dutch oven. Bake covered at 450 for 20 minutes.
Uncover the loaf and top with caramelized onions, thyme, and gruyere cheese. Continue baking at 425 for 20 minutes. Your crust should be nice and golden brown when it is done. If you aren’t sure if your loaf is completely cooked, use a thermometer to see if the internal temperature reaches 190 F.