Step 1

To make the cake: Preheat oven to 175°C/350°F. Butter three 6-inch (15 cm) cake pans and dust them with cocoa powder.

Step 2

Melt the butter, add milk and set aside to cool.

Step 3

In a large bowl, mix together the flour, baking soda, cocoa powder, sugar and salt. Add the butter mixture, eggs and sour cream to the dry ingredients and mix until just combined. Add the hot coffee and stir until smooth (batter will be quite liquid).

Step 4

Divide the batter evenly between the three cake pans. Bake the cakes on the lower rack for 32-35 minutes or until a cake tester comes out clean. Let the cakes cool in their pans for 15 minutes, then invert onto a cooling rack and allow to cool completely.

Step 5

To make the chocolate filing: Place chocolate in a saucepan together with butter, over low heat. Stir often until everything is melted. Add a pinch of salt. Let cool to spreadable consistency – meanwhile you can prepare the frosting.

Step 6

To make the chocolate hazelnut frosting: In a standing mixer fitted with the paddle attachment, beat butter until pale and creamy, about 2 minutes. Add the cream cheese, powdered sugar, chocolate hazelnut spread and salt and beat until frosting is completely smooth and fluffy. If frosting feels loose, place the bowl in the fridge for a while.

Step 7

Assemble the cake: Place the first cake layer on a plate or cake stand. Spread with chocolate filling, then pipe or spread a layer of frosting on top (save some frosting for the second layer as well). Don’t pipe or spread all the way out to the edge as the weight of the cake will make it spread.

Step 8

Place the second layer on top of the first layer. Spread second layer with chocolate filling, then pipe or spread a layer of frosting on top. Put the third layer on top. Put the cake in the fridge to stabilize it while you prepare the dark chocolate glaze.

Step 9

To make the chocolate glaze: Coarsely chop the dark chocolate and place it in a saucepan together with butter, over low heat. Stir often until melted. Add a pinch of salt. Let cool slightly but make sure it doesn’t thicken too much, it should still be liquid. Pour the glaze over the cake and quickly spread it over the edges of the cake to make it run down the sides.

Step 10

Keep cake in the fridge but serve it in room temperature.