In a deep pot, heat oil to 380 degrees F. In a small bowl, beat egg.
Cut chocolate into 1/2-inch cubes. Take an egg roll wrapper, and brush edges with egg wash, and lay on a work surface, wash side up, with a point facing you, not a straight edge. Place about 2 ounces of chocolate 1 or 2 inches from the edge, and top with 1/4 cup of microwaved marshmallow or fluff.
Fold the corner closest you up and just over the filling, press lightly, then fold in the sides, making a little pull or tuck to keep the roll right. Then roll away from you and press to seal tightly. (Take care not to tear the egg roll wrapper. This can cause roll to leak while cooking. If tear occurs, pinch dough together until it reseals or discard wrap and use a new one.) Repeat until all egg rolls are formed.
Fry egg rolls 4 at a time, turning almost immediately, cooking on all sides to just golden brown, less than a minute. (Make sure not to overcook filling. If you see marshmallows start to ooze out before both sides are golden, filling will be overcooked and egg roll will appear hollow inside) Remove to a paper towel-lined plate and repeat until all cooked. Make sure to check your oil temperature between additions.
When ready to serve, dust with powdered sugar and graham cracker crumbs. Serve immediately, but caution very hot!