Preheat the oven to 350°F.

Butter a 9x13-inch pan and set aside.

Sift flour, sugar and 1/2 teaspoon salt together in a large bowl.

Whisk to combine, then set aside.

Beat eggs, baking soda, buttermilk and 1 teaspoon of the vanilla together in a separate bowl, then add to flour mixture and stir well.

Transfer batter to the prepared pan and bake for 35 minutes, or until a toothpick inserted into the center of the cake comes out clean. Cool cake in pan.

Melt remaining 1/2 cup butter, 3 tablespoons cocoa and milk in saucepan.

Once butter is fully melted, remove saucepan from heat and whisk in powdered sugar, remaining 1/4 teaspoon salt, remaining 1 teaspoon vanilla and pecans until well combined.

Spread evenly over the top of the cooled cake.
(If desired, to lower fat content, one of the two sticks of butter used in making the cake can be replaced by 1/2 cup applesauce. This step, however, would likely lead to a denser cake.)