Pour the cream into a large oven dish. The dish should be big enough so that the cream sits over a wide surface area and be between ½- to 1-inch in depth.

Put the cream in the oven for 12 hours.

Remove the cream from the oven. A thick skin should have formed over the top.

Let the cream cool to room temperature, then put the dish in the fridge for 12 hours.

Scrape off the thickened layer that has formed and transfer to a mixing bowl. Discard the liquid.

Mix thoroughly until you have a smooth, thick clotted cream.