In a Dutch oven, pour in 64 ounces of chicken stock and add a small bunch of fresh sage. Heat over medium heat until the mixture just begins to simmer, letting the sage infuse its aromatic flavor into the broth. This should take about 5 minutes.

While the stock simmers, take your large head of garlic, peel the cloves, and halve them. Add the garlic to boiling water and boil for 3-4 minutes until tender. Drain and mash the garlic until smooth.

Stir the mashed garlic into the simmering chicken stock and allow the mixture to simmer for another 10 minutes, stirring occasionally.

In a jar, combine the egg yolk with 1 teaspoon of Dijon mustard and a pinch of salt. Add olive oil and use an immersion blender to blend until creamy. Incorporate the egg white for a thicker consistency if desired.

For a velvety texture, strain the soup using a fine-mesh sieve to remove any solids, ensuring it is smooth and creamy.

Slowly temper the mayonnaise by adding a few spoonfuls of the hot soup into it, whisking continuously. Pour this blend back into the Dutch oven and stir gently over low heat.

Ladle the finished soup into bowls, garnish with croutons, a drizzle of olive oil, smoked paprika, and freshly chopped parsley. Serve hot.