Instructions:
- Preheat oven to 350°F (175°C). Grease and flour two 9-inch cake pans, lining the bottoms with parchment paper circles.
- Prepare Pecan Crunch Filling/Topping: Cream softened butter and brown sugar until fluffy. Beat in the flour and salt until just combined. Stir in the chopped pecans. Set aside half this mixture for the topping; press the remaining half evenly into the bottom of the prepared cake pans.
- Mix Dry Cake Ingredients: Whisk together the cake flour, granulated sugar, cocoa powder, baking soda, baking powder, and salt in a large bowl.
- Mix Wet Cake Ingredients: In a separate bowl, whisk eggs, buttermilk, oil, and 2 teaspoons of vanilla extract until uniform.
- Combine: Gently mix the wet ingredients into the dry ingredients until just incorporated. Do not overmix.
- Activate Batter: Carefully whisk in the hot water or hot coffee until the batter is smooth and runny.
- Layer & Bake: Divide the cake batter evenly over the pecan base layers in the prepared pans. Bake for 30–35 minutes, or until a wooden skewer inserted near the centre comes out with moist crumbs attached.
- Cool Slightly: Let cakes cool in the pans for 15 minutes before carefully inverting them onto a wire rack to cool completely.
- Make the Glaze: Whisk sifted powdered sugar and cocoa powder. Add melted butter, 1 teaspoon vanilla extract, and milk, mixing until a smooth, thick but pourable glaze forms. Add milk slowly until the desired consistency is reached.
- Assemble: Place the first layer glaze-side up. Spread a thin layer of glaze over the first layer. Top with the second layer. Pour remaining glaze over the top, allowing it to drip down the sides.
- Final Topping: Immediately sprinkle the reserved pecan crunch mixture generously over the wet glaze.
- Set: Allow the glaze to set slightly at room temperature for about 30 minutes before slicing and serving.