Marshmallow Whoopie Pies

Preheat oven to 375°F.

In a large mixing bowl, cream butter and sugar until light and fluffy. Add the eggs and vanilla; mix well. Combine the flour, cocoa, baking soda and salt; add to the creamed mixture alternately with water and yogurt, beating well after each addition.

Drop by teaspoonfuls 2 inches apart onto greased baking sheets. Bake for 5–7 minutes or until set. Remove to wire racks to cool completely.

For the filling: In a small mixing bowl, beat filling ingredients until fluffy. Spread filling on the bottom of half of the cookies; top with remaining cookies.