Preheat your oven to 375°F (190°C) and line a baking sheet with parchment paper.
Unroll the crescent roll dough and separate into triangles.
Spread about 1 teaspoon of Nutella onto each triangle, leaving a small border around the edges.
Roll up each triangle from the wide end to the narrow tip to form crescent shapes.
Place on the prepared baking sheet and brush with a lightly beaten egg if using.
Bake for 10-12 minutes, or until golden brown and flaky.
Let cool slightly, then dust with powdered sugar before serving.