The Fudge Mines of Flatheadia had definitely begun their clandestine work after the fall of the Great Underground Empire in 883, though some say the first extraction facilities were erected immediately after the turning of the castle’s west wing to fudge in 785. If this earlier date is accurate, these may not have originally been mines, as many tons of the fudge covered the landscape and washed lusciously into subterranean streams, and being magic, affected what ate it. In response, Lord Dimwit Flathead the Excessive ordered the west wing to be covered over and a new wing was constructed upon the first and declared Flatheadia Fudge (as it became known) illegal.

Despite the royal ban, Flatheadia Fudge became a black market staple during the rebuilding period, after several of Dimwit's balloons carrying the fudge to his Fenshire melting plant was hit. Tons of the sweet chocolate was squirreled away in vaults while fresh foundations and tunnels were created throughout the valley floor - ostensibly to replace the original west wing.
Both royal and black market mine shafts were dug into the earth. When any of these regenade distilling operations, which purified the fudge ore back into edible confections, were found out, their shafts were shutup with the King's seal. The Flatheadian Fudge reserves were mammoth, and entire mounds were left beneath the rocky soil. Many of these sealed entrances, still today, dot the regions surrounding the White House.

Although Flatheadia had been reduced into the White House in 883, even during the Second Age of Magic, the region where the west wing of the castle had once sat, still emitted a scent like carob or cocoa tea, while the accompanying rivers and ponds on the surface were still tainted with flows of chocolate and infested with magical chocolate animals.

During the Great Monster Uprising, "Detective Softly", as this otherwise anoynomous man was known, found entrance into the Fudge Mines. As he was treading ground near the White House, the washed out earth beneath him gave way to a sinkhole which dropped him into a shaft.

SOURCE(S): Zork Zero, Zork: Grand Inquisitor, Legends of Zork (game, personal correspondence with author of 'A Wizard and His Cocoa' quest)