Mary's Original Chocolate Cake

This is a page out of Mary's recipe book.

It is in her handwriting. 

She didn't write any instructions but her method had to be watched to be understood.

Here is what AI tells me:

AI Overview

The "cake method with boiling water and baking soda" typically refers to a chocolate cake recipe known for its moist and rich results. The boiling water and baking soda play crucial chemical roles in the batter, which is often very thin. This technique is especially effective for chocolate cakes because it blooms the cocoa powder, releasing more flavor. 

How the boiling water and baking soda method works

Baking soda reacts with cocoa: Natural, non-alkalized cocoa powder is acidic. The addition of baking soda, an alkali, creates a chemical reaction that produces carbon dioxide gas. This gas provides lift, or leavening, to the cake.

Boiling water accelerates leavening: The heat from the boiling water accelerates the reaction between the baking soda and the acidic ingredients, causing the batter to get an initial boost of leavening before it even enters the oven.

Boiling water creates moisture and tender texture: The hot water hydrates the cocoa and flour, ensuring a moist crumb. The thin batter that results from adding boiling water helps produce a very tender and delicate texture. 

Key steps for a "boiling water" chocolate cake

Combine dry ingredients: In a large bowl, whisk together the flour, sugar, cocoa powder, baking soda, baking powder, and salt.

Combine wet ingredients (except water): In a separate bowl, or directly into the dry ingredients, add the eggs, milk, vegetable oil, and vanilla extract. Mix until combined.

Add boiling water: Carefully stir in the boiling water until the batter is smooth. The batter will be very thin, but this is normal for this method.

Bake immediately: Pour the batter into your prepared pan and bake right away while the leavening agents are still active. Delaying could cause the cake to turn out flat and dense. 

Another version is at: 

https://www.hersheyland.com/recipes/hersheys-perfectly-chocolate-chocolate-cake.html