In a heavy-bottomed saucepan, bring the sour cream to a gentle simmer over medium heat. Let it boil for about 5 minutes, stirring occasionally to prevent the cream from burning.

Sift one-third of the flour into the simmering sour cream, whisking vigorously to prevent lumps from forming. Continue to simmer the mixture over medium-low heat until the butterfat begins to separate and rise to the surface, which takes about 10 minutes.

Carefully skim off the separated golden butterfat using a spoon and transfer it to a small, heat-proof bowl. Keep this liquid fat warm, as it will be used as a traditional topping for the finished porridge.

Whisk the remaining flour into the sour cream mixture until completely smooth and thick. Gradually pour in the warm whole milk, whisking continuously until the porridge becomes incredibly creamy and lump-free.

Simmer the porridge for an additional 5 minutes to cook out the raw flour taste, then stir in the kosher salt. If the mixture appears too thick, add a splash more warm milk until you reach your desired consistency.

Ladle the hot porridge into serving bowls and drizzle the reserved melted butterfat over the top. Serve immediately, generously sprinkled with granulated sugar and ground cinnamon for the perfect sweet and savory balance.