Bring cream and butter to a boil over medium-high heat in small saucepan. Remove from heat and sprinkle chocolate over cream mixture; let stand 1 minute. Stir with wire whisk until smooth; stir in nuts. Chill in refrigerator until firm, about 1 hour.
Lay egg (what?) roll wrapper on work surface. Spoon 1 rounded tablespoon of chocolate filling into center of wrapper, shaping chocolate into elongated shape. Brush edges of wrapper with water. Fold in sides and roll up very tightly. Cover with plastic wrap and refrigerate until needed.
In a large heavy skillet, heat 3/4" oil to 350°F Fry spring rolls in small batches until golden, Turning once, about one minute per side. Transfer with slotted spoon to paper towels to drain. Sprinkle with powdered sugar just before serving, if desired.