Heat oven to 325F for dark/coated cupcake tins. Prepare cupcake tins with greaseproof liners. Set aside.
In stand mixer, add spice cake mix, eggs and butter and mix to combine on low speed. While on low, add in pumpkin, water and oil. MIx on low, then slightly increase speed to medium for 1 minute. Stir in pecans. Divide batter between cupcake tins.
Bake for 17-19 minutes, or until a toothpick inserted in the center comes out clean. Let cool in pans for 10-15 minutes then turn out on wire rack to cool completely.
Cinnamon Cream Cheese Frosting
In a stand mixer, beat butter and cream cheese together until light and fluffy. Add in 2 cups powdered sugar and mix slowly to combine. Add in vanilla and cinnamon and 2 more cups powdered sugar. Mix to combine. Scrape down sides of bowl to make sure everything is incorporated. Add last cup of powdered sugar, mix, then scrape down sides of bowl. Beat on medium for 2-3 minutes until light and fluffy.
Prepare piping bag with French start piping tip and pipe on frosting. Alternatively, use an offset spatula for more rustic looking frosting. Garnish with chopped pecans or sprinkles. Refrigerate if not eating immediately. Before serving, let sit at room temperature for a few minutes so frosting is not solid and cupcake is not cold.