Add eggs and sugar to the bowl of a food processor (see notes for making by hand); pulse until creamy and pale yellow, about 2 minutes. Be patient and let the sugar and eggs get to the creamy texture. Add orange zest, liquor, and vanilla extract, and process until combined.

Add flour and baking powder to the mixture and pulse until a few times (not too much). Add the butter pieces and pulse until thoroughly combined. The dough will be sticky.

Wrap the dough in a sheet of plastic wrap and refrigerate for 30-45 minutes.

When the dough is chilled, transfer it to a lightly floured surface. Divide dough into four even sections.

Roll each section into a long rope, about the same thickness as your finger. Cut each rope of dough into sections ½ to 1-inch wide. Hint: I prefer mine to be slightly larger than the standard marble size. 

Roll each section into small balls in the palms of your hands – the balls should be the size of a hazelnut or marble (they will puff up when frying!). Place the dough on a parchment-lined baking sheet and cover them with a clean kitchen towel as you roll out all the balls. 

Prepare a large plate or baking sheet with a few layers of paper towels. Set it next to your stove.

Add oil to a heavy-bottomed pot set over medium-high heat. Allow the oil to reach a frying temperature of 350°F. (Use an instant-read candy thermometer to determine the oil temperature). Or, test one dough ball to see if bubbles form around it, and it quickly turns a golden brown color. 

Fry dough balls in hot oil (batches of about 15). Stir a couple of times until puffed and golden brown, about 2 minutes. Use a slotted spoon to help the dough balls move in the oil to get a nice, even golden brown color.

Use a slotted spoon to remove the dough balls, carefully shake the excess oil back into the pan, then transfer the fried dough to the paper towel to absorb the excess oil. Repeat frying with the remaining dough.

Add honey and orange juice to a small saucepan over medium heat. Stir to combine. Cook, continuously stirring with a wooden spoon, until the honey is runny, about 5 minutes.

Transfer the fried dough balls to a large mixing bowl. Pour the honey mixture on top of the struffoli and toss to combine until the struffoli are fully coated with the honey mixture. 

Spray a tall cylindrical drinking glass with non-stick cooking spray and set it in the center of a round serving platter, plate, or cake plate (alternatively- use a springform pan to set and shape the struffoli balls). You can also serve them in a large mound on a serving plate. 

Use a rubber spatula to mound the glazed struffoli balls to form a wreath around the glass. 

Allow the struffoli to set for 2-3 hours (you can make up struffoli until this part 1 day in advance).

Before serving, remove the glass from the center of the wreath. Sprinkle liberally with rainbow nonpareils. (note: serve within 3 hours of adding sprinkles, or their color will start to melt into the honey. It will still taste delicious even if the sprinkles melt).