Preheat oven to 140°C and grease a 9-inch round cake pan.
Sift cake flour, cocoa, sugar, baking powder, baking soda, and salt into a large bowl.
Whisk eggs, buttermilk, oil, and vanilla in a separate bowl until smooth.
Add wet ingredients to dry and mix until just combined.
Pour in boiling coffee while whisking until the batter is glossy and thin.
Pour batter into prepared pan and bake 40-45 minutes until a toothpick tests clean.
For caramel: melt sugar until amber, stir in butter, then carefully add cream and cook until smooth.
Beat cream cheese, powdered sugar, and vanilla until fluffy; spread over cooled cake.
Drizzle warm caramel over the cream topping and serve.