Preheat your oven to 400°F (200°C). Slice the top off the garlic bulb, drizzle with olive oil, wrap in foil, and roast for 30-40 minutes until soft.

While the garlic roasts, pour chicken stock into a pot, bring to a gentle boil, add sage and salt, then simmer for 10 minutes.

Once garlic is roasted, let it cool slightly, squeeze out the cloves, and mash into a paste.

In a bowl, whisk together the egg yolk and Dijon mustard until well blended.

Gradually add olive oil while whisking until thick and creamy, then stir in the garlic paste.

Temper the egg mixture by adding a ladleful of hot stock, then slowly mix it back into the rest of the stock.

Heat the combined soup gently without boiling. Serve warm, garnished with olive oil or fresh herbs.