In a heavy-bottomed saucepan, heat the sour cream over medium-low heat. Let it gently simmer for about 5 minutes, stirring occasionally to prevent scorching.

Sift half of the all-purpose flour (about 6 tablespoons) into the simmering sour cream. Whisk vigorously to combine and prevent any lumps from forming.

Continue to simmer the mixture gently over low heat for 10-15 minutes until the butterfat begins to separate and pool on the surface. Carefully skim off this yellow fat with a spoon and reserve it in a small bowl.

Once you have skimmed off the fat, whisk the remaining flour into the sour cream mixture until fully incorporated and smooth.

Gradually whisk in the warm whole milk, pouring a little at a time to keep the porridge perfectly smooth. Stir in the kosher salt and let it simmer for another 5 minutes until thick and creamy.

Ladle the warm Rømmegrøt into shallow bowls. Drizzle the reserved melted butterfat over the top, sprinkle generously with cinnamon and sugar, and serve immediately alongside traditional cured meats if desired.