Preheat your oven to 350°F (175°C) and prepare three 8-inch round cake pans by greasing them with butter or non-stick spray and lining with parchment paper.

In a large bowl, combine eggs, sour cream, granulated sugar, and dark brown sugar. Whisk until smooth and creamy.

In a separate bowl, sift together all-purpose flour, cocoa powder, baking soda, and baking powder.

Dissolve cocoa powder and instant coffee in 1 cup of boiling water, stirring until mixed, then incorporate into the wet ingredients.

Slowly add dry ingredients to wet ingredients, gently folding together until just combined.

Divide the batter among prepared cake pans and bake for 25-30 minutes or until a toothpick comes out clean.

Let the cakes cool in the pans for 10 minutes before transferring them to wire racks to cool completely.

Prepare salted caramel sauce by cooking sugar, butter, and heavy cream over medium heat until smooth, then let cool.

Beat cream cheese until creamy, then add cocoa powder and powdered sugar, and gradually beat in heavy cream and melted dark chocolate.

Trim the tops of the cooled cakes for even layers. Spread frosting between layers and drizzle with salted caramel.

Garnish the assembled cake with additional salted caramel sauce and a sprinkle of flaky sea salt.