Preheat oven to 350°. In a large bowl, beat sugar, oil, pumpkin and eggs until well blended. Combine flour, baking soda, salt, baking powder and pumpkin pie spice; gradually beat into pumpkin mixture until well blended. Fill paper-lined muffin cups two-thirds full. Bake 18-22 minutes or until a toothpick inserted in center comes out clean. Cool 10 minutes before removing from pans to wire racks to cool completely.

For filling, combine cornstarch and milk in a small saucepan until smooth. Bring to a boil, stirring constantly. Remove from heat; cool to room temperature. In a large bowl, cream shortening, butter and confectioners’ sugar until light and fluffy. Beat in vanilla if desired. Gradually add cornstarch mixture, beating until smooth. Using a sharp knife, cut a 1-in. circle 1 in. deep in the top of each cupcake. Carefully remove tops and set aside. Spoon or pipe filling into cupcakes. For the top I used Cream Cheese Frosting

Frosting:

In a medium bowl, cream together the cream cheese and butter until creamy. Mix in the vanilla, then gradually stir in the confectioners’ sugar. Store in the refrigerator after use.