Preheat oven to 350. Spray a half sheet baking pan with cooking spray. (Use the sheet pan you have with the highest edges for best results, at least 16 x 12!)

For the cake: In a saucepan, add the butter, water and cocoa and bring to a boil. Let it boil for just a minute, then remove from the heat and let it sit for a minute or two.

In a large mixing bowl whisk together the flour, sugar and salt.

Pour the warm chocolate mixture over the flour mixture and stir together until combined with no lumps.

Combine the buttermilk, eggs, baking soda, and vanilla.

Whisk that mixture in to the chocolate mixture.

Pour the batter in to your prepared sheet pan and make sure it is spread completely evenly. Smack the pan on the counter gently a couple of times.

Bake at 350-degrees for 18-20 minutes until it’s just baked through. Don’t overcook!

Let the cake cool for 15-20 minutes.

For the glaze: Chop pecans finely. (I pulse them a few times in my ninja chopper.)

In a saucepan melt the butter, add the cocoa and stir until it just comes to a boil then turn off the heat.

Add the milk, vanilla, and powdered sugar. Whisk together till the lumps of powdered sugar are gone. Stir in the pecans.

After the cake has cooled for 15-20 minutes, pour the glaze over the top of the cake so that it reaches the sides of the pan, then let the cake sit for at least an hour or two which will make it easier to slice.