Rømmegrøt is a porridge made with sour cream, milk, and a bit of flour, and then topped with cinnamon and sugar. Norwegians usually serve rømmegrøt with a glass of raspberry juice on the side, as well as sometimes cured meat and Norwegian flat bread.
Cook the sour cream in a covered saucepan on medium heat for about 5 minutes.
Turn down the heat and add half of the flour and stir well with a whisk. Once the flour is fully incorporated, let the mixture continue to cook, stirring occasionally, until fat starts to release. Use a spoon to gather as much of the fat as you can in a small bowl, saving for later. (Don't worry if you can't get any fat - in that case you can add butter later.)
Whisk in the rest of the flour and then slowly add the milk, whisking constantly to avoid lumps. Let the porridge continue to cook on low heat for 5 minutes and then add salt.
Serve with sugar, cinnamon, and the fat from the porridge. If you're using lower fat sour cream you can top the rømmegrøt with some butter instead.