Not that kind of "cake"

A propos of nothing: I've just discovered the phrase "the cake of custom". One of the OED's (subscription only) definitions of "cake" is "A mass or concretion of any solidified or compressed substance in a flattened form, as a cake of soap, wax, paint, dry clay, coagulated blood, tobacco, etc." It goes on to give the figurative usage, "1872 BAGEHOT Physics & Pol. (1876) 27 To create what may be called a cake of custom. 1879 H. GEORGE Progr. & Pov. X. i. (1881) 433 A body or 'cake' of laws and customs grows up."

Update

In Physics and Politics, Bagehot also wrote of "breaking the cake of custom"

What is most evident is not the difficulty of getting a fixed law, but getting out of a fixed law; not of cementing (as upon a former occasion I phrased it) a cake of custom, but of breaking the cake of custom; not of making the first preservative habit, but of breaking through it, and reaching some-thing better.