A lyric from "I Can Cook Too" written by Leonard Bernstein which appears in the 1944 Broadway musical "On the Town" sung by Nancy Walker and later in the 1949 film.

https://en.wikipedia.org/wiki/On_the_Town_(musical)

I heard it last night at the end of the final episode of Julia S1, E8 Chocolate Souffle (May 5, 2022).

https://www.imdb.com/title/tt10975574/

The phrase "now you're coking with gas" was coined by American Gas Association publicist Carroll Everard "Deke" Houlgate. Deke's son indicated that his father "planted it with Bob Hope's writers" and it was ultimately used in one of his radio shows. From there it turned into one of his catchphrases and it was adopted by others including The Jack Benny Program and Maxwell House Coffee Time.

Incidentally, Houlgate was also a football journalist who devised the first college football rankings methodology that determined the national champions from 1929 to 1958.

Is this the same Houlgate, or perhaps his son who played for USC Trojans in the 1931 and 1932 Rose Bowl games?

References: (see also and check...) - A Way With Words co-host Martha Barnette https://soundcloud.com/waywordradio/now-youre-cooking-with-gas

https://www.b98.tv/video/wise-quacking-duck/

"Say. Now you're cooking with gas." Daffy Duck in an oven bathing himself in gravy.

The Wise Quacking Duck Warner Bros. (1943)<br /> Looney Tunes cartoon directed by Bob Clampett. <br /> Released on May 1, 1943