Step 1

Heat oven to 350°F (177°C). Lightly butter a 5x7-inch baking dish and set aside.

Step 2

Stir together the flour, sugar, baking soda, and salt in a medium-sized mixing bowl. Set aside.

Step 3

In a 1-quart saucepan, heat the butter, water, and cocoa powder over medium-low heat, stirring frequently until mixture comes to a light simmer and butter has completely melted. Remove from heat and pour over flour mixture in the bowl; stir until well mixed.

Step 4

Stir in egg white, milk, cinnamon, and vanilla.

Step 5

Pour into the baking dish and bake for 25-30 minutes, or until a toothpick inserted in the center comes out clean.

Step 6

Melt butter in a small 1-quart saucepan over low heat.

Step 7

Add the cocoa powder and milk and stir until the mixture begins to simmer.

Step 8

Once the mixture is simmering, remove from the heat and whisk in powdered sugar (a little at a time), vanilla, and cinnamon. Whisk constantly until the frosting is smooth.

Step 9

Stir in the nuts.

Step 10

Spoon the warm frosting over the top of the cake. Use a rubber spatula to smooth out and spread if needed. Allow the cake to cool, then slice and enjoy.