Mix together flour and sugar in bowl. In saucepan put milk (1 cup), butter, and cocoa. Whisk together and stir till mixture melts. After it melts, pour over flour and sugar. Mix well. Add lemon milk (1/2 cup), soda, eggs and vanilla. Stir well. Pour into baking pan (13 x 9).Bake at 400 for 20 minutes or until toothpick comes out clean. Do not over-bake or cake will be dry. Icing
1 Stick Butter
4 Tbsp. Cocoa
6 Tbsp Milk
1 Box Powdered Sugar (4 cups)
1 tsp Vanilla
1 Cup Pecans

Heat butter, cocoa, and milk in a saucepan till melted. Stirring frequently. Bring to a boil. Remove from heat. Stir in sugar, vanilla. Beat with spoon till smooth and glossy, but not too stiff. Add nuts and pour over warm (not hot) cake.

This will set up rather quickly (like fudge). This old frontier recipe was used before Ranchers/farmers had availability of block chocolate or chips, only powdered cocoa which was expensive. It is sometimes called Texas Sheet, but originally called “Sheath” cake because the icing covered the cake like a “sheath” covers a knife.