Whoopie Pies

1. In a medium saucepan over low heat, melt together butter, chocolate chips and brown sugar. Let cool for five minutes.
2. In a large bowl beat eggs with vanilla. Whisk in chocolate mixture.
3. Sift together flour, baking soda and salt. In several additions, whisk dry ingredients into batter. Chill for two hours until very cold, or overnight.
4. Preheat oven to 325° F.
5. Scoop batter using a 1-2-inch ice cream scoop (or two large spoons). Space cookies two inches apart on a parchment-lined baking pan. Use hot water to keep the scoop clean.
6. Using the inside of your hand, flatten the mounds of dough about halfway.
7. Bake cookies about 10 minutes for two-inch cookies (adjust baking time for size), just until they begin to rise and loose their sheen.
8. Cool completely on the pan set over a rack, then fill with buttercream.
9. Store chilled, but serve room temperature.

For Pumpkin Cream Cheese Frosting

1. With a hand mixer (or stand mixer with a paddle), beat cream cheese on medium-low speed until smooth, then slowly add one cup powdered sugar.
2. Beat in pumpkin to taste, then add vanilla, salt and heavy cream.
3. Beat in remaining powdered sugar a little at a time, stopping when you reach your desired sweetness level.

Vanilla-Marshmallow Butterceam

1. Beat butter with a hand mixer (or stand mixer with a paddle) on medium-high speed until lightened in color, about five minutes.
2. Beat in powdered sugar on low speed a little at a time, scraping down the bowl often. 
3. Beat in vanilla, salt and heavy cream. Beat in marshmallow fluff.