Thaw the puff pastry roll as per the package instructions, ideally overnight in the refrigerator for even thawing. Preheat the oven to 400°F (200°C). Lightly dust your work surface with flour, unroll the puff pastry, and gently peel off any attached parchment paper. Dust the top of the pastry with a small amount of flour as well.

Using a sharp knife or a pizza cutter, divide the puff pastry into four equal squares. Cut each square diagonally from corner to corner, forming two triangles per square. You should have a total of eight triangles.

Place each triangle with the widest end closest to you. Spread a heaping teaspoon of Nutella on the wide end of each triangle. Begin rolling tightly from the wide end toward the pointed tip, creating a crescent shape. Repeat for all triangles.

Arrange the rolled croissants on a baking sheet lined with parchment paper, ensuring space between each for even cooking. Brush the croissants with the egg wash (a mixture of the beaten egg and water) for a glossy finish.

Place the baking sheet in the preheated oven and bake for 20–25 minutes, or until the croissants are puffed and golden brown. Keep a close eye during the last few minutes to avoid over-baking.

Remove the croissants from the oven and allow them to cool slightly. Dust generously with icing sugar before serving.