brownie
n.a small, square chocolate cake that is soft and thick. It often has nuts inside and is very sweet.
n.a small, dense, chocolate-based baked confection, typically square or rectangular in shape. Often contains nuts or chocolate chips and has a texture between a cake and a soft cookie.
“I baked a batch of brownies for the party.”
“The bakery is famous for its fudge brownies, which are served warm with a scoop of vanilla ice cream.”
“While traditional recipes call for cocoa powder, many modern variations use melted dark chocolate to achieve a richer, more decadent brownie texture.”
Countable when referring to the individual squares; uncountable when referring to the substance in general.
From brownie (“a helpful elf”). Specifically, inspired by the story "The Brownies" by Juliana Horatia Ewing (published in 1870, The Brownies and Other Tales), in which two children, Tommy and Betty, learn that children can be helpful brownies or lazy boggarts. But compare with Dutch kabouter (“a very young female member of the scout movement”) (literally, a "gnome").
From Brown + -ie.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.