In blender or food processor, finely chop chicken livers, a few at a time.
When all are chopped, return to blender and add soy sauce, butter, onion salt, mustard, nutmeg and hot pepper sauce. Blend until smooth and well mixed, scraping down sides frequently.
Add water chestnuts and bacon. Mix in thoroughly by hand. Spoon into 1 large or 5 small molds, pressing firmly so all air pockets are removed.
Chill. Unmold by dipping quickly into hot water up to rim and allow to soften to room temperature before serving. Garnish with green onion.
Serve with melba toast. Makes about 1 1/2 cups