Lay half (20) of the wonton wrappers out on a clean, dry counter surface. Spoon all of the Nutella a heaping teaspoon at a time into the center of each wonton until all of the Nutella is evenly distributed among the wontons.
In a small bowl, beat the egg with a fork. Add the cold water and mix well.
Use a small pastry brush or your finger to apply the egg mixture to the outside edges of each wonton. Discard any leftover egg wash.
Top each wonton with the remaining 20 wonton wrappers. Pinch the edges together so they seal well and the Nutella won’t escape when the wonton is fried.
Add vegetable oil to a large pot to approximately 2 inches depth. Heat the oil over medium-high heat to 350 degrees.
Very carefully, add a couple of the filled wontons to the hot oil using a metal slotted spoon. Fry on each side until golden brown, approximately 1 minute per side. Remove the fried wontons from the hot oil and cool on paper towels or a metal cooling rack.
Repeat step 6 until all wontons have been fried.
Add the powdered sugar to a sifter and sprinkle over the fried wontons.
Scoop the raspberry jam into a small, microwave safe bowl. Heat for about 30 seconds on high, then stir well until melted. Be careful, it’s very hot! Allow the jam to cool slightly before serving.
Serve the fried Nutella wontons with the melted raspberry jam for dipping.