Preheat oven to 180 degrees F.
Pour heavy cream into an 8" by 8" baking dish or something similar.
Place baking dish into a larger 13" by 9" inch dish and fill outer dish with hot water about 1/2 way up sides.
Place baking dish in the center of the oven, uncovered and bake for 10-12 hours. Cream will have a dark golden skin and appear wrinkled.
Remove baking dish from the oven and allow to cool about 1 hour. Place in the refrigerator for an additional 8 hours undisturbed.
Remove baking dish from the refrigerator. Carefully scrape the top layer of the cream or "clout" off the top and place in a mixing bowl. There will be some liquid left. Reserve it to thin the cream if necessary.
Mix the cream so that the yellow crusty parts mix in with the white cream and add any reserved liquid to the clotted cream to achieve a spreadable consistency.
Pack clotted cream in small ramekins or a mason jar and refrigerate until ready to use.