Preheat your oven to 350°F (175°C). In a mixing bowl, whisk together the wet ingredients: eggs, milk, vegetable oil, vanilla extract, and sour cream until smooth.

In another bowl, combine the all-purpose flour, granulated sugar, dark brown sugar, cocoa powder, baking powder, baking soda, and salt. Mix dry ingredients until blended.

Gradually add the dry ingredients to the wet mixture, stirring until fully incorporated. Aim for a smooth batter.

Mix together cocoa powder with 1 cup boiling water and instant coffee until smooth. Fold this cocoa mixture into your cake batter.

Pour the batter evenly into three greased 8-inch round cake pans. Bake for 30-35 minutes until a toothpick comes out clean.

In a saucepan over medium heat, combine sugar and water until dissolved and golden brown. Add heavy cream, butter, and salt, whisking until smooth.

In a bowl, beat together cream cheese, cocoa powder, powdered sugar, and a pinch of salt until smooth. Gradually incorporate heavy cream and melted dark chocolate.

Once cooled, level the cake layers. Place one layer on a platter, spread frosting, and drizzle salted caramel sauce. Repeat with the second layer.

Top with the third layer and cover with remaining frosting.

Drizzle additional salted caramel on top and optionally garnish with chocolate shavings or sea salt.