In a mixing bowl, combine the eggs, sugar, oil and pumpkin. In another bowl, combine the flour, baking soda, salt, baking powder and cinnamon; add to pumpkin mixture and beat until well mixed. Fill paper lined muffin cups two-thirds full. Bake at 350°F for 18-22 minutes or until a toothpick comes out clean. Cool for 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; cook and stir constantly for 2 minutes or until thickened. Remove from the heat; cool to room temperature. In a mixing bowl, cream shortening, butter and sugar and vanilla. Gradually add the cornstarch mixture beating until light and fluffy.

Using a sharp knife, cut a 1 inch circle 1 inch deep in the top of each cupcake. Carefully remove tops and set aside. Spoon or pipe filling into cupcakes. Replace tops.