Heat oven to 350 degrees F (175 degrees C). Grease and flour pan; set aside. In medium bowl, beat butter and sugar on medium speed until light and fluffy. Blend in eggs. Add flour, ginger, cinnamon, baking soda, baking powder and salt; blend on low speed 1 minute. Add sour cream and mix on medium speed until well blended. Divide batter into 4 equal parts. Divide first portion of batter among walnut-shaped wells in pan. To second portion of batter, add 1 or 2 drops of brown food coloring; mix well. Divide this portion of batter among acorn-shaped wells. To third portion of batter, add 1 or 2 drops of orange food coloring; mix well. Divide this portion of batter among pumpkin-shaped wells. To last portion of batter, add melted bittersweet chocolate; mix well. Divide batter among pinecone-shaped wells. Bake for 10-15 minutes, until toothpick inserted comes out clean. Cool 10 minutes in pan. Invert pan onto cooling rack and cool completely. If desired, shapes can be sandwiched together with buttercream frosting or acorn tops can be dipped in melted chocolate and rolled in finely chopped nuts. Makes 24 cakelets.