Cocoa Loaf Cake

The notebook that I'm taking these new recipes from is very brittle so I'm taking the recipes in order. I apologize that there will be quite a few days of cakes, but if I jump around to make it more interesting I'm afraid that pages will be lost before I can get them transcribed. Today's recipe is like a lot of grandma's recipes - a list of ingredients. I'm sure that grandma felt that any good baker would know exactly what to do with the list.

1 cup sugar
1 egg
2 Tbsp. butter
1/2 cup cocoa
1 cup sour milk
1 tsp. soda
1 1/2 cups flour
1 tsp. vanilla