Preheat the oven to 350F. Grease a 13x18" baking tray with butter and dust with an even layer of cocoa powder. Shake off the excess, and set aside.

Roughly chop the pecans. Heat up a pan with 1 tablespoon butter over medium heat, and add the pecans. Stir and toast until fragrant, nutty and they start to brown. Remove from heat and set aside.

Melt butter in a saucepan over medium heat and sift in the cocoa powder. Whisk it together until smooth and pour in the boiling water. Place back on stove on medium and heat until it comes to a boil. Remove and let it cool down a bit.

In a large bowl, beat together both sugars and the oil. Beat in the eggs until pale in colour, about 2-3 minutes. Add in the buttermilk and vanilla and combine.

Pour the butter and cocoa powder mixture into the egg mixture and beat until completely combined.

Mix together the flour, salt and baking soda in a small bowl and add to the wet ingredients. Beat until JUST combined. Don't overmix it.

Pour and spread the batter evenly onto the baking tray. Bake for 15-20 minutes or until a toothpick inserted comes out clean and is springy to the touch.

While the cake is baking, make the frosting. Combine the butter, cocoa powder, and milk in a saucepan (I use the one from before) and place over medium heat. Cook until the butter melts and the mixture starts to slightly thicken a bit, while stirring. Remove from heat and whisk in the powdered sugar and salt until smooth. Mix in the pecans.

While the cake is still warm, pour over the chocolate glaze and spread evenly.

Cut into even slices and enjoy!