Step 1Beat the egg whites with 3 tablespoons of powdered sugar until thick but not dry. Place the gelato in a mixing bowl and stir until smooth; don't let it become too liquid. Fold in the egg whites. Spoon the mixture into each cup, dividing evenly. Smooth the top with a spatula. Sprinkle on the remaining crumbs. Freeze at least 2 hours or as long as 1 week, covered airtight.
Step 2Whip the cream and the remaining 1 tablespoon of sugar until thick. Add the amaretto. Mix well. (This can be made several hours ahead and refrigerated, covered airtight.)
Step 3To serve, let the biscuit tortonis sit at room temperature for 10 minutes. Top each with about 2 tablespoons of the amaretto cream. Serve immediately.