Prepare pies:

1. Bake sweet potato (or microwave) until tender, allow to cool and peel and discard skin.
2. In a mixing bowl with an electric mixer whip sweet potato, 1 tablespoon butter, 1/2 cup cream, sour cream and vanilla until light and creamy.  Set aside.
3. Sift together dry ingredients.
4. Cream together light brown sugar and 1 stick room temperature butter until light and fluffy.
5. Add eggs one at a time beating after each addition.
6. Add sweet potato puree and blend until combined.
7. With mixer on low speed, add dry ingredients alternating with buttermilk ending with dry.
8. Drop mixture onto a parchment-lined baking sheet in level spoonfuls, using a medium cookie scoop or pipe batter from a piping bag to make 1 1/2 inch rounds.
9. Bake at 350 degrees for 10-12 minutes.  Cool completely on wire racks.

Prepare filling:

1. Combine mascarpone, Frangelico and honey BY HAND, stirring just until mixed.  Do not over mix.  It will cause the mascarpone to begin to break down.

Assemble:

1. Turn half the whoopie pies over and dollop each with a spoonful of filling, about 2 tablespoons (or pipe from a piping bag) onto one side.  Top with remaining whoopie pie halves and press gently to spread filling to the edges.  Roll edges in desired toppings.  Serve immediately.  Pies may be placed on a parchment-lined baking sheet, covered in plastic wrap and frozen for 8 hours until firm.  Store in an airtight container for up to 3 weeks.