Set up a small ice bath.
In a pan, heat extra-virgin olive oil over high heat, then toss in spinach with salt. Cook for about 1 minute. Remove spinach and shock in a bowl of cold ice water. Place spinach in a clean dish towel and wring spinach dry by twisting and squeezing. Using a knife, chop the spinach extremely finely.
Meanwhile, take the warm boiled potatoes, peel them, and run them through a food mill on smallest setting, or a ricer. Add the chopped spinach to the potatoes, and mix to combine. Make well in center of the spinach potato mixture, add the flour, egg, and salt, and knead to form a dough.
Bring 6 quarts water to boil and add 2 tablespoons salt.
Roll the dough into 1-inch thick ropes and cut into 1-inch long pieces. Flick the dough off the tines of a fork to establish the classic gnocchi shape. Drop 10 to 15 gnocchi at a time into boiling water. When they float, all together, remove the gnocchi to the ice bath. Drain well. Repeat until all the gnocchi have been boiled.
In a 12 to 14-inch saute pan, mash together the Gorgonzola and the butter until smooth. Add the grappa and simmer until the liquid evaporates, about 4 minutes. Toss gnocchi into pan with the Gorgonzola and butter until well combined. Add chopped parsley and a handful of chili flakes and chives. Pour into warmed pasta bowls and serve.