1. Line an 8- x 4-inch loaf pan with plastic wrap, allowing 2 to 3 inches to extend over sides.
2. Combine espresso and rum in a shallow bowl. Brush or quickly dip one-third of ladyfingers (about 8) on both sides in espresso mixture, and place in bottom of prepared loaf pan.
3. Layer 1 cup ice cream over ladyfingers, and sprinkle evenly with one-third grated chocolate. Repeat 2 times with remaining ladyfingers, espresso mixture, ice cream, and grated chocolate.
4. Cover and freeze at least 3 hours or until ready to serve. Invert pan onto a serving platter, and remove pan and plastic wrap. Cut into 1 1/2- or 2-inch slices. Garnish, if desired.