Ingredients

Cookies:
2 cups all-purpose flour
1 cup granulated sugar
1/2 cup unsweetened cocoa powder
1 teaspoon baking soda
1/2 teaspoon baking powder
1/4 teaspoon salt
1/2 cup sour milk
1/2 cup water
1/2 cup shortening
2 eggs

Filling:
1/2 cup shortening
2 tablespoons flour
1 tablespoon granulated sugar
1 teaspoon vanilla extract
1 teaspoon mint extract
1/8 teaspoon salt
2 1/2 cups powdered sugar
3-4 tablespoons milk
green food coloring
chopped nuts

Directions

Preheat oven to 400 degrees. To make cookies: combine the flour, granulated sugar, cocoa powder, baking soda, baking powder and salt. Add the sour milk, water and shortening. Beat with mixer on low speed until combined. Beat on medium speed 2 minutes more. Add eggs and beat another 2 minutes. Drop by rounded spoonfuls 2 inches apart onto a cookie sheet. Bake about 8 minutes until the top springs back when touched in the center. Remove from oven and transfer to a wire rack to cool.

Meanwhile, make the filling: Combine shortening, flour, sugar, vanilla and mint. Beat on medium speed for 30 seconds. Add food coloring and beat. Slowly add 1 1/4 cups of the powdered sugar, beat well. Add milk. Gradually add the rest of the powdered sugar, beat until light and fluffy. Spread filling on the flat bottom of one cookie, top with another cookie and sandwich together. Continue until you have used all the cookies.