Use heavy cream with a high fat content
Pour the cream into a shallow oven-safe dish
Heat the oven to a low temperature, about 180°F to 200°F
Place the dish in the oven for 8 to 12 hours
Remove the dish and let it cool to room temperature
Refrigerate the cooled cream for several hours or overnight
Skim the thick clotted layer from the top
Stir gently if needed before serving