The Phrase Finder has this entry: [emphasis added]
Indicating 'intensive emphasis of what someone else has just said,' and how! is a long-popular catchphrase first recorded in 1924. The Americanism possibly derives from the German 'und wie!' or the Italian 'e come!', meaning the same thing, and once very common among Americans of German and Italian extraction, respectively." From "Encyclopedia of Word and Phrase Origins" by Robert Hendrickson (Facts on File, New York, 1997).
etymonline has a brief mention:
And how! emphatic, first recorded 1865. The formulation was common in book and article titles by then (such as The National Debt, and How to Pay It), but Pennsylvania writer Bayard Taylor, in whom it is first recorded, seems to regard it as a German or German-American expression.
Someone was saying the other day,
Everybody knows that Spanky of the Little Rascals invented this phrase.