In a saucepan, combine 2 whole eggs + 1 yolk, 120 ml milk, 120 ml whipping cream, and 25 g sugar. Cook on low heat, stirring frequently, until it reaches a gentle simmer (do not boil).

Pour the hot mixture over 200 g dark chocolate. Let sit for 5 minutes, then stir until silky smooth. Press cling wrap directly onto the surface and refrigerate for at least 2 hours.

In a mixing bowl, combine 250 g cream cheese, 1 tsp vanilla, 15 g cocoa powder, and 30 g powdered sugar. Mix until smooth.

While mixing, pour in 120 ml cold whipping cream and beat until smooth and creamy. Add the chilled chocolate crèmeux and mix again until fully combined. Cover with cling wrap (touching the surface) and refrigerate for at least 1 hour.

Preheat oven to 160°C (320°F). Line a 13” × 10” tray (or 13” × 9” pan) with parchment.

In a large bowl, whisk together 250 g brown sugar, 160 ml buttermilk, 160 ml vegetable oil, and 120 g plain yogurt. Add 2 eggs and 1 tsp vanilla, whisk until well combined.

Sift in 280 g flour, 1 tsp baking powder, 2 tsp baking soda, and ½ tsp salt. Mix just until incorporated.

In a jug, stir together 250 ml hot water, 1 tbsp instant coffee, and 50 g cocoa powder until smooth.

Pour the cocoa–coffee mixture into the batter and whisk until smooth. Pour into the prepared pan and bake for 30–35 minutes.

Cool the cake completely. Cut into 4” × 8” pieces to fit a loaf pan. Slice each piece horizontally to create more layers, if desired.

Line a 4” × 8” loaf pan with parchment. Add a cake layer, pipe/spread the chocolate filling, then repeat layers as you like (cake → filling → cake → filling).

Refrigerate for at least 4–5 hours or overnight before slicing and serving.