Line 12 cup muffin pan with paper muffin liners. Place a bowl and rotary beater in the refrigerator to chill.
Pour cold water in a small bowl. Sprinkle gelatin evenly over water and let stand 5 minutes to soften.
Stir softened gelatin into 1/2 cup boiling water with mustard and cayenne. Stir until gelatin is completely dissolved. Chill in the refrigerator, stirring occasionally until it begins to gel.
Put ham through a food chopper. Fold ham, pimiento and sweet pickle into gelatin.
Using chilled bowl and beater, whip cream until it piles softly. Fold whipped cream into the ham gelatin mixture. Spoon into baking cups. Chill 2 to 3 hours until firm.
When ready to serve, arrange lettuce cups on a platter or tray and invert molds onto lettuce cups, removing paper liners.