Preheat oven to 350 F. and arrange rack in center. Generously coat 2 (6-cup) round-bottom (mini-ball) pans with melted butter.

Whisk together flour, cinnamon, baking powder, ginger, salt and cloves in a medium bowl; set aside. Combine molasses, water and baking soda in another bowl; set aside.

Beat together softened butter and sugar in a mixing bowl on medium speed until light and fluffy, about 2 minutes. Beat in egg, then pumpkin puree until combined well. Alternately beat in flour mixture and molasses mixture, in 2 batches, scraping down sides of bowl with a rubber spatula, and beating until just combined. Evenly divide batter among cups in prepared pans.

Bake until cakes spring back when lightly pressed, about 20 minutes. Transfer cakes in pans to rack and let stand until cool enough to handle, 10 to 15 minutes. Run a flexible knife or spatula around edges of each cake and invert onto rack; let cool completely. If cakes have a dome, trim off to sit flat. (Can be made ahead. Store in an airtight container at room temperature up to 1 day.)

Roll out each fondant block into a 17-inch round, about 1/ 8 inch thick. Using a 5-inch round cutter, cut out 4 rounds from each. Place 1 round over each cake and smooth to mold, trimming excess from bottom edge. Using a plain tip, pipe the icing in a straight line from one end of each cake down the center to the opposite end, then pipe 3 lines down each side to make pumpkin ridges. Place 1 piece of string candy in the center of each cake to create a stem. (Can be madeahead. Place decorated cakes in an airtight container and store at room temperature up to 10 hours.)