I had it as a child -- possibly. Very tasty, too. A version of the venerable sugar cream pie, one of the Symbols of Indiana. (Not kiddin'!) I was very young at the time and perhaps I had misremembered? No-one else appeared to have heard of it.
So was it a dream? The name seemed unlikely...until today! Wiki-wandering, "Chess pie" turned up and there it was: an offhand mention of the closely-related, "Vinegar pie" which "generally adds somewhere between a teaspoonful and tablespoonful of vinegar to the above ingredients to reduce the sweetness." Hah! It does exist!
3 weeks ago