Chill the Nutella for easier filling. Spoon Nutella into a small piping bag or zip-top bag, push it toward one corner, and refrigerate. This makes it thicker and easier to pipe later.

Make the cinnamon sugar. In a shallow bowl, mix the granulated sugar with cinnamon and a small pinch of salt. Set aside for rolling the fresh-fried poppers.

Start the dough base. In a medium saucepan, combine water, butter, sugar, and salt. Bring to a gentle boil over medium heat, stirring to melt the butter.

Add the flour. Once boiling, remove from heat, dump in the flour all at once, and stir vigorously with a wooden spoon. Return to medium heat and cook, stirring constantly, for 1–2 minutes until the dough forms a smooth ball and a thin film coats the pan.

Cool slightly, then add eggs. Transfer the dough to a mixing bowl and let it cool 3–5 minutes so it doesn’t scramble the eggs. Beat in the vanilla. Add the eggs one at a time, mixing well after each until the dough is glossy and pipeable. It should be thick but smooth, dropping slowly from a spoon.

Heat the oil. Pour 2–3 inches of oil into a heavy pot. Heat to 350–360°F (175–182°C). Keep a thermometer handy to maintain temperature.

Pipe the dough. Transfer the dough to a piping bag fitted with a medium round or star tip. Pipe 1–1½-inch mounds onto a parchment-lined tray, or pipe directly into the hot oil, snipping with scissors for even pieces. Work in small batches to avoid crowding.

Fry until golden. Fry for 3–4 minutes total, turning halfway, until deep golden brown and puffed. Adjust heat to keep oil in range—too hot will brown the outside before the inside cooks.

Drain and coat. Remove with a slotted spoon, drain on a rack or paper towels for 30 seconds, then immediately roll in cinnamon sugar so it sticks. Repeat with remaining dough.

Fill with Nutella. Fit your chilled Nutella bag with a small round tip (or snip a tiny corner). Use a skewer to poke a small hole in each popper, then pipe in Nutella until you feel it plump slightly. Don’t overfill or it may burst.

Serve warm. Enjoy right away while crisp and gooey. If you like, drizzle with more Nutella or serve with a dipping sauce.