Preheat your oven to 350°F (175°C).
Unroll the crescent roll dough and separate it into triangles.
In a mixing bowl, combine the chopped pecans, brown sugar, corn syrup, melted butter, vanilla extract, and ground cinnamon. Stir until fully combined.
Take about 1 tablespoon of the pecan mixture and place it at the wide end of each triangle. Roll the dough from the wide end to the point, enclosing the filling completely.
Brush the tops of the crescent rolls with the beaten egg and bake for 12-15 minutes until golden brown.
Let them cool for a few minutes and dust with powdered sugar if desired.