In a large Dutch oven or stock pot, heat the chicken stock and fresh sage. Let it simmer gently while you prepare the garlic.

Peel the garlic cloves, slice them in half lengthwise, and remove the embryonic shoot from each clove to prevent bitterness.

Boil the garlic cloves for 3-4 minutes, then drain and mash them finely. Add the mashed garlic to the simmering stock and cook for 10 minutes.

For the mayonnaise, blend egg yolk, mustard, salt, and oil in a jar with an immersion blender until thick. If needed, add the egg white to thicken the mayonnaise.

Optional: Strain the soup for a smoother texture and return it to the pot.

Temper the mayonnaise by stirring a ladle of hot soup into it. Whisk the tempered mayonnaise into the soup pot.

Heat the soup without boiling to prevent curdling.

Serve the soup with crusty croutons, a drizzle of olive oil, a sprinkle of smoked paprika, and fresh parsley if desired.