Chocolate Ganache Whoopie Pie Cake

15.25 oz. chocolate fudge cake mix

3.9 oz. box instant chocolate fudge pudding mix

3/4 c. water

3/4 c. oil

4 eggs

1 c. sour cream

1 t. vanilla

Marshmallow Creme Filling:

10 T.  butter, room temperature

7 oz. jar marshmallow creme

pinch of salt

1 1/2 t. vanilla

1 c. powdered sugar, divided

Chocolate Ganache:

1/2 c. milk chocolate chips

3 T. whipping cream

Preheat the oven to 350. Spray a bundt pan. Dust with flour. Combine 1st 7 ingredients until well blended. Pour batter into bundt pan and spread evenly. It is a very thick batter. Bake 45 minutes or until toothpick comes out clean. Remove from oven and cool in pan for 10 minutes. Invert onto plate or wire rack and cool completely. Once cool, slice horizontally. In a large bowl, combine first 4 ingredients of creme filling. Mix until well combined using hand mixer. Add 1/2 cup of powdered sugar and mix until combined. Add remaining powdered and mix until creamy and smooth. Spread over bottom half of cake and place the top half of cake over creme filling. Place chocolate chips in small bowl and set aside. Microwave whipping cream until it starts to bubble. Pour over chocolate chips and allow to sit for 5 minutes. Stir until smooth and creamy. If chips aren't completely melted, place in microwave and heat, stirring every 10 seconds, until chocolate is melted. Pour over cake and place in refrigerator until set. Slice to serve.