Preheat oven to 350 degrees. Line 24 muffin cups with paper liners.
Place spice mix in a large bowl and stir with a whisk to remove any lumps.
Add sweet potato, buttermilk, vegetable oil, and eggs and stir together until smooth.
Fill muffin cups 3/4 full and bake for 20 to 25 minutes, until firm on top.
Remove from oven and let cool in pans for several minutes. Remove from pans to cool completely.
For frosting, using an electric mixer beat cream cheese and butter together until creamy and smooth,. With mixer on, slowly add maple syrup.
Add cinnamon, allspice, and salt.
Gradually add in confectioners' sugar, turning mixer to low-speed with each addition and up to medium-high between additions to mix well. Beat until smooth.
Spread frosting on cupcakes. Decorate with pecan halves if desired.