In a large bowl, combine sugar, pumpkin, eggs, and oil, whisking until blended.
In another large bowl, combine flour, baking powder, baking soda, cinnamon, ginger, clove, pumpkin pie spice, and salt.
Add the dry ingredients to the wet ingredients, stirring until combined. Do not overmix.
Line 18 regular-sized muffin cups with paper liners, and fill them 3/4-full with batter.
Bake at 350 degrees for 20-25 minutes, or until edges are golden, and a toothpick inserted near the center of a cupcake comes out clean.
Remove from heat, and cool for 10 minutes before removing cupcakes from pans to wire racks to cool completely.
Using a spoon or cookie scoop, scoop a 1-inch ball out of the center of each cupcake. Using 1 cup Nutella, spoon a rounded teaspoonful into the center of each cupcake.
With remaining Nutella and remaining ingredients, prepare Nutella buttercream. Top cupcakes with Nutella Buttercream!