My family called it Wacky Cake:
1 1/2 c. flour
1 c. sugar
1 sq. bitter chocolate or 1/4 c. cocoa
1 tsp. vanilla extract
1/2 tsp. salt
1 tsp. baking soda
1 tsp. vinegar
1/3 c. Mazola or Wesson oil🙂
1 c. cold coffee
Mix and pour into a greased and cocoa dusted non stick 8x8” square cake pan. Bake at 375* for 20 mins. We always liked it with buttercream frosting.