Preheat your oven to 400°F (200°C). Slice the top off the large garlic bulb to expose the cloves, then place it on a baking tray. Drizzle generously with extra virgin olive oil, ensuring it's well coated. Roast for 30-40 minutes until the garlic is soft, golden, and aromatic.

While the garlic roasts, add 64 ounces of chicken stock to a large pot. Bring to a gentle boil over medium heat, then stir in the dried sage and salt. Reduce heat to a simmer.

Once the roasted garlic is cool enough to handle, squeeze the softened cloves from their skins into a bowl. Mash the garlic into a smooth paste while warm.

In a separate bowl, whisk together the egg yolk and Dijon mustard. Slowly drizzle in the remaining olive oil while whisking to create a creamy emulsion.

With the stock simmering, gently fold the mashed garlic into the pot. Whisk in the emulsion, ensuring everything blends together smoothly. Simmer for an additional 3-5 minutes.

Ladle the warm soup into bowls, pairing it with roasted baguette slices. Top with crispy pancetta or fresh herbs if desired.