In a shallow bowl, combine sugar and cinnamon.

In a saucepan, melt butter with water and a pinch of salt over medium heat until just boiling.

Remove from heat and stir in flour until thick dough forms.

Beat in eggs one at a time until smooth and glossy.

Heat oil in a deep pot to about 350 °F (175 °C).

Using a small scoop or spoon, drop bite-sized portions of dough into hot oil in batches. Fry until golden brown, about 2–3 minutes, turning as needed.

Drain on paper towels briefly, then toss while still warm in cinnamon-sugar mixture until fully coated.

Once cooled slightly, use a toothpick or piping bag tip to fill each bite with Nutella. Serve warm.