In a large Dutch oven, pour in 4 cups of chicken stock and add a handful of fresh sage. Heat over medium heat until it begins to gently simmer, about 5 minutes.

While the stock simmers, take 10 cloves of garlic, remove their skins, and slice them in half lengthwise. Place the garlic in a saucepan of boiling water and blanch for 3-4 minutes to mellow the flavor.

Add the mashed garlic to your simmering stock in the Dutch oven, stirring well to combine. Let the mixture simmer on low heat for about 10 minutes.

In a narrow jar, combine the egg yolk, 1 tablespoon of Dijon mustard, and a pinch of salt. Slowly drizzle in 1 cup of olive oil while blending with an immersion blender until it emulsifies smoothly.

Optionally strain the soup through a fine-mesh sieve for a velvety texture. Temper the mayonnaise by whisking in a ladle of the hot soup until well mixed, then gradually whisk it back into the pot.

Once warmed through and silky smooth, ladle the soup into bowls. Garnish with homemade croutons, a drizzle of olive oil, a sprinkle of smoked paprika, and fresh parsley if desired.