When was "what's cooking" first used?

Question

Does anyone know when the expression "what's cooking" began to be used in the United States? I'm interested because I'm writing a novel set in 1933.

A contributor on Quora found examples from 1939. Are there any examples earlier than that?

Answer 1

GDoS (Green’s Dictionary of Slang) has usage examples from the ‘20s, so you can probably use it safely in your context:

What’s cooking:

lit. ‘what’s going on?’, i.e. what is happening?; thus negative response nothing cooking.

1926 Maines & Grant Wise-crack Dict. 11/2: Nothing cooking – Nothing doing.

1944 H. Brown Walk in Sun 77: What’s cooking, Jack?