pretzel vs twice-baked bread

pretzel

noun
  • A toasted bread or cracker usually in the shape of a loose knot. 

  • Anything that is knotted, twisted, or tangled. 

verb
  • To bend, twist, or contort. 

twice-baked bread

noun
  • A type of sweet raised bread baked for a second time in order to render it brown, hard, and crisp. 

How often have the words pretzel and twice-baked bread occurred in a corpus of books? (source: Google Ngram Viewer )