In a small bowl stir together the gelatin and water. Let stand 5 minutes.
Meanwhile, in a medium saucepan combine the whipping cream, eggnog, sugar, and salt. Heat, stirring occasionally, over medium heat until hot. Remove from heat. Stir in gelatin mixture. Cool slightly, about 10 minutes, stirring occasionally (stirring prevents the gelatin from sinking to the bottom). Immediately pour into dishes as directed in Layer 1.
LAYER 1 Divide Eggnog Custard among ten 6-ounce coffee cups, tea cups, or small dishes. Loosely cover with plastic wrap. Refrigerate about 2 hours, until set.
LAYER 2 Sprinkle nutmeg on custard.
LAYER 3 In a small bowl whisk together the jam and lemon juice. Spoon into each cup, spreading to cover custard. Refrigerate 2 hours or overnight.
LAYER 4 To serve, top each trifle with a star-shape sugar cookie.