Preheat your oven to 400°F (200°C). Spread the sliced garlic bulb on a baking tray and drizzle lightly with a bit of olive oil. Roast for 30-40 minutes, until the garlic is soft and golden. This deepens the flavor and brings out its sweetness.

While the garlic is roasting, pour the chicken stock into a large pot. Bring it to a gentle boil over medium-high heat. Once boiling, add the dried sage and a pinch of salt, then lower the heat to a simmer.

After roasting, remove the garlic from the oven and use a fork to mash it into a smooth paste. I like to do this while the garlic is still warm—it mashes more easily.

In a small bowl, whisk the egg yolk with Dijon mustard until smooth. Slowly drizzle in the remaining olive oil while whisking continuously to create a creamy emulsion.

Stir the mashed roasted garlic from Step 3 and the emulsified egg mixture from Step 4 into the hot chicken stock from Step 2. Whisk well to blend. Serve the soup hot, optionally with roasted slices of baguette on the side.