Baked sponge cake with a fruit preparation, commonly jam, or pineapple rings in syrup, at the base of the pan, so as to form the top of the cake when turned out.


Upside-Down Cake
Image: www.delightfulrepast.com/


The term 'upside down' is known at least since 1340 (OED), but with reference to cake only since the end of the 19th Century.