Place shelled, unsalted pistachios in a food processor and process until crumbly. Add honey and vegetable oil and process until a paste is formed, about 5 minutes. Scrape into a bowl and set aside.

Heat milk, vanilla extract, and salt over medium heat in a medium sized saucepan. Whisk in the pistachio paste until smooth. Set aside.

In a bowl, whisk together egg yolks and sugar until smooth. Add all-purpose flour and whisk until fully incorporated. Pour half the heated milk mixture into the bowl with the eggs and immediately whisk until smooth.

Place the saucepan with the milk back on the burner over medium heat. Pour the egg/milk mixture from the bowl into the saucepan and whisk continuously until it thickens, about 5 minutes. Immediately remove it from the heat.

Transfer to a bowl and place a sheet of plastic wrap on the surface of the cream to prevent a skin from forming while it cools. After a few minutes, transfer to the refrigerator to cool completely, for 2-3 hours.

Prepare the dough according to the instructions for the Sicilian brioche dough recipe until step #7 (first 3 hour rising period).

Divide the dough in half. Roll out the dough on a lightly floured surface to ½ inch thickness. Cut into rounds using a 3-inch doughnut cutter or glass.

Reroll the scraps to cut out more bomboloni, or roll the dough into small balls for mini doughnut balls. Continue with the remaining dough.

Place the bomboloni on 2 parchment paper covered baking sheets. Let rest in a warm part of your kitchen for 1.5 hours, or until doubled in bulk.

Place about 2 inches of vegetable oil in a fryer or heavy-bottomed pan. Heat the oil until a wooden spoon handle bubbles when submerged.

Cut the parchment paper into squares around the bomboloni. Use the parchment paper to carefully lift the bomboloni and place into the hot oil. Fry only 3-4 bomboloni at a time.

Fry for about 1 minute on each side, until golden brown. Transfer to a paper towel lined tray to absorb excess oil.

Toss the bomboloni in granulated sugar while still warm. Let cool a few minutes before filling.

Place the cooled pistachio custard cream in a pastry bag fitted with a star tip. Make a small hole on the side of each bomboloni and pipe in the pistachio filling until the sides swell.