Put the bacon in a pot over medium-high heat and cook, stirring occasionally, until the bacon renders its fat.

Lower the heat to medium. Add the onion, leek, potato, and cabbage and cook, covered, stirring occasionally, until tender, about 10 minutes. Add the wine and cook for 2 minutes more. Add the stock, bring to a boil, and season with salt and pepper, to taste. Lower the heat and simmer until the potato is tender. Add the cream and simmer for a few minutes until the soup achieves a creamy texture. Remove from the heat and finish by whisking the butter cubes into the soup. (Don't re-boil the soup after adding the butter into it, or it will curdle.)

Divide the soup among bowls, drizzle with basil oil, and garnish with the fried basil leaves.