Flour Mixture
1. Sift together flour, cocoa, baking soda, salt and chopped nuts.
2. Add sugar gradually to the shortening, creaming well. Blend vanilla. Beat eggs, one at a time.
MILK-VINEGAR MIXTURE
1. Combine whole milk and vinegar.
2. Thoroughly blend in flour mixture alternately with milk-vinegar mixture beginning and ending with flour.
3. Pour into prepared baking pans.
4. Bake in the turbo broiler for 30 to 35 minutes at 350°F / 175°C.
5. Top with marshmallow and semi-sweet chocolate chips and sprinkle with chopped nuts. Let it cool then serve.