Step 1

Preheat the oven to 350°F and lightly grease a 9 by 13-inch cake pan.

Step 2

Sift the flour, sugar, baking soda and salt into a medium mixing bowl.

Step 3

Place the margarine in a small saucepan and when melted, add the cocoa and water and bring to a boil.

Step 4

Add the boiling cocoa mixture to the dry ingredients and stir until just combined.

Step 5

Add the pareve milk and white vinegar, eggs, and vanilla and stir until smooth.

Step 6

Pour into prepared baking dish and bake until a toothpick inserted in the center of the cake comes out clean, 35 to 40 minutes.

Step 7

Sprinkle the marshmallows over the cooled cake.

Step 8

Melt margarine in a medium saucepan, add the cocoa powder and pareve milk and white vinegar, and bring to a boil.

Step 9

Remove from the heat and add the confectioners’ sugar, vanilla, and salt and stir until very smooth.

Step 10

Pour the hot icing over the marshmallows on the hot cake and sprinkle with the nuts.

Step 11

Let cool to lukewarm before serving.

Step 12

Cake is best served warm or at room temperature.