The site of Martha Clara Vineyards is the largest parcel for sale on Long Island’s East End

After his family sold Entenmann’s, the famed baked goods company, Robert Entenmann bought a farm on Long Island’s North Fork. But he didn’t abandon his heritage: The roughly 8,000-square-foot house he built on the property has a commercial-grade “baking room,” for whipping up tasty treats.

“It’s in the genes,” said Sheri Winter Clarry of the Corcoran Group, who is now listing the Jamesport property on behalf of…