In a medium saucepan, heat the heavy cream over medium heat until it starts to simmer. Stir frequently to prevent scorching.

Reduce the heat to low and slowly whisk in the flour, stirring constantly to avoid lumps. Cook for 2-3 minutes until the mixture thickens into a smooth paste.

Gradually add the milk while whisking continuously, ensuring the mixture remains smooth. Increase the heat to medium and cook until the mixture thickens, about 10 minutes.

Add the butter, granulated sugar, and salt. Stir well until the butter is fully melted and incorporated into the porridge.

Remove the rommegrot from the heat and let it cool slightly before serving.

Serve warm in bowls, topped with ground cinnamon, granulated sugar, and a dollop of butter for authentic flavor.