Cream is a special portion of milk that is greatly enriched with fat. This enrichment occurs naturally thanks to the force of gravity, which exerts more of a pull on the milk’s water than on the less dense fat globules. Leave a container of milk fresh from the udder to stand undisturbed, and the globules slowly rise through the water and crowd together at the top. The concentrated cream layer can then be skimmed off from the fat-depleted “skim” milk below. Milk with 3.5% fat will naturally yield cream that is about 20%.