flapjack vs sponge cake

flapjack

noun
  • A pancake. 

  • A bar made of (though not limited to) rolled oats, butter, golden syrup, and brown sugar, baked in a tray. 

sponge cake

noun
  • A light, soft, baked dessert (commonly layered with cream and jam) that is typically made with flour, sugar, baking powder and eggs, and has a firm, yet well aerated structure, similar to that of a sea sponge. 

How often have the words flapjack and sponge cake occurred in a corpus of books? (source: Google Ngram Viewer )