Big Tex's Texas Sheet Cake: A Chocolatey Crowd-Pleaser!

Ingredients

• 2 cups (250g) all-purpose flour, plus more for dusting the pan
• 2 cups (400g) granulated sugar
• ½ teaspoon (2.5ml) baking soda
• ¼ teaspoon (1.25ml) salt
• 1 cup (240ml) unsalted butter (2 sticks), cut into cubes
• 1 cup (240ml) water
• 4 tablespoons (20g) unsweetened cocoa powder
• ½ cup (120ml) buttermilk
• 2 large eggs
• 1 teaspoon (5ml) vanilla extract
• 6 tablespoons (30g) unsweetened cocoa powder
• 6 tablespoons (90ml) milk
• 4 cups (480g) powdered sugar, sifted
• 1 cup (100g) chopped pecans or walnuts