Jamie Oliver Chocolatey Tiramisu

Ingredients:\r
• 250g good-quality dark chocolate (70% cocoa solids)\r
• 50g butter, diced\r
• sea salt\r
• 175g sponge fingers\r
• 400ml good hot sweetened coffee\r
• Vin Santo or other sweet dessert wine\r
• 6 large eggs, preferably free-range or organic\r
• 100g caster sugar\r
• 750g mascarpone\r
• 2 oranges\r
• a few fresh coffee beans, bashed up finely