Bring the sour cream to a gentle simmer in the Dutch oven over medium-low heat.

Whisk in the flour a little at a time, stirring constantly, until the butterfat begins to separate and rise to the surface.

Skim off the golden butter and set it aside.

Gradually whisk in the warmed milk until the porridge is smooth and pourable. Season with salt.

Ladle into bowls, drizzle with the reserved butter, and dust with cinnamon sugar.