3 cups all-purpose flour
1 1/2 teaspoons baking soda
1/2 teaspoon salt
1/2 cup buttermilk
1/2 cup rolled oats
1/2 cup white sugar
1/2 cup dry milk powder
1 tablespoon butter
1/3 cup water
1/2 cup unsalted butter
1 egg
Preheat oven to 375 degrees F (190 degrees C). In a medium bowl, mix together flour, baking soda, salt and buttermilk. Stir in oats, sugar, milk and dry milk. Press mixture evenly into a 9x13 inch baking pan.
Spread 1/2 of the mixture on the bottom of the prepared pan. Bake in the preheated oven for 5 minutes. Let cool. Meanwhile, in a small saucepan over medium heat, melt 1/2 of the butter, stirring frequently until smooth. Slowly pour 1/3 of the milk over the three layers and blend them well.
Spread half of the butter mixture over the layers and then spread another 1/3 of the milk over the top, then pour the remaining mixture over the whole pan. Let cool. In a small bowl, beat egg until thick, then break egg into cooled milk mixture and beat again until smooth. Pour over the cookies and the milk mixture.
Bake for 25 to 30 minutes or until a knife inserted into the center comes out clean. Let cool 5 minutes before removing from pan. Cool completely before removing from pan.