01 -
Preheat oven to 175°C. Lightly grease a 44.5 x 31.75 cm jelly-roll pan.
02 -
Combine cola, oil, and cocoa powder in a medium saucepan over medium-high heat. Bring to a boil, stirring frequently. Remove from heat.
03 -
In a large bowl, whisk together flour, granulated sugar, brown sugar, baking soda, and salt until thoroughly blended.
04 -
Add the warm cola mixture to the dry ingredients, then whisk in buttermilk, beaten eggs, and vanilla extract until smooth. Pour batter evenly into the prepared pan.
05 -
Bake at 175°C for 18 to 22 minutes, or until a wooden pick inserted in the center comes out clean.
06 -
While cake bakes, melt butter and chopped chocolate together in a medium saucepan over medium-low heat, stirring until smooth. Remove from heat, then whisk in milk and cola until combined. Stir in powdered sugar and vanilla. Beat with an electric mixer at medium speed until smooth.
07 -
Pour warm frosting evenly over the warm cake, spreading gently to edges. Sprinkle with toasted chopped pecans. Allow to cool completely before serving.