Richard Nixon's favorite snack was reportedly cottage cheese topped with ketchup.
A 1960 article in the LA Times
treated this as noncontroversial personal information about the then-presidential candidate, noting that he had acquired a taste for this unusual delicacy from his Quaker grandmother.
Los Angeles Times - Mar 14, 1960
However, by the 1970s Nixon's team was downplaying his fondness for this snack. Helen Smith, the first lady's press secretary, dismissed it as overblown rumor.
Casper Star Tribune - June 5, 1973
Similarly, White House chef Henry Haller, in his book The White House Family Cookbook
, denied he had ever seen Nixon eat such a concoction:
"If the President ever doused his cottage cheese with catsup, I never saw him, and doubt he ever did."
I suspect the truth is that Nixon enjoyed this snack when he was younger, but didn't continue eating it when he was President. Regardless, the combination of cottage cheese and ketchup was definitely associated with Nixon in the public mind, and it inspired one odd work of art.
In 1973, on the eve of Nixon's second inauguration, the sculptor Carl Andre dumped 500 pounds of cottage cheese on the floor of the Max Protetch gallery in Washington, DC. He then topped this with 10 gallons of ketchup. He called the work 'American Decay'. However, it smelled so bad that it all had to be removed the next day.
More info: Interview Magazine
'American Decay'. Image source: bonhams