Marshmallow Sandwhich Cookies

2 cups flour
1 tsp baking soda
1/4 tsp salt
1/4 cup unsweetened cocoa
1 cup sugar
1 egg
1/3 cup oil
1 tsp vanilla
3/4 cup milk
1/2 cup butter
1 cup powdered sugar
1/4 cup marshmallow creme

Grease cookie sheets. Set aside. In a large mixer bowl, combine flour, soda, salt, coca, and sugar. Make a well in center of mixture. Add egg, oil, vanilla and milk. Beat until smooth. Drop by rounded teaspoonfuls onto prepared cookie sheets. Bake 10 minutes at 350. Cool on wire rack. In a small mixer bill, combine. Utter, powdered sugar, and marshmallow creme. Beat until smooth. Spread the cream filling on half the cooled cookies. Top with remaining cookies.