Preheat oven to 350°F (175°C), grease and line two 9-inch pans with parchment.
In a large bowl, whisk together flour, sugar, cocoa, baking soda, baking powder, and salt.
In a separate bowl, beat eggs, then add buttermilk, coffee, oil, and vanilla extract. Mix well.
Gradually add wet mixture to dry ingredients, mix until smooth batter forms.
Divide batter evenly into prepared pans and bake for 28–32 minutes or until a toothpick comes out clean.
Heat cream in a saucepan until simmering. Pour over chopped chocolate in a heatproof bowl.
Let sit for a minute, then whisk until smooth. Stir in butter, corn syrup, and salt. Let ganache cool slightly.
Cool cakes completely. Spread ganache between layers, then cover top and sides using offset spatula and bench scraper.
