Beat whipping cream at high speed with an electric mixer until soft peaks form; fold in sour cream, sugar, and vanilla.
Note: Otherwise known as clotted cream, Devonshire cream is a specialty of Devonshire, England. It's made by heating rich, unpasteurized milk and, after cooling, removing the thickened cream that forms a top layer. In our version, sour cream mocks the thick texture of the real cream.
