Preheat the oven to 180°C (160°C for fan assisted ovens)/Gas Mark 4. Lightly grease 2 x 32cm x 22cm Swiss roll tins and line the bases and sides with baking paper.
Stir the cake mix, oil, water and eggs gently together in a bowl, then whisk (by hand or electric mixer) for 2-3 minutes until smooth and creamy. Divide the mixture equally between the 2 cake tins, using a palette knife to spread the cake mixture to the corners of the tins and to level the surfaces. Bake for 15 minutes until risen, golden and springy to the touch. Leave to cool in the tins; about 30 minutes.
Turn the cakes out onto large cake boards and peel off the baking paper. Using a 6cm round cookie cutter, stamp out 12 rounds from each cake. Place all the rounds on the boards and freeze for 2 hours.
Meanwhile, make the praline. Lightly grease a large baking sheet. Place the granulated sugar and water in a heavy-based saucepan or deep frying pan. Heat gently over a medium heat, stirring, until the sugar has dissolved and the liquid is clear. Increase the heat and let the syrup come to the boil, without stirring. Boil for 4-5 minutes or until the syrup is a deep golden caramel colour (see Tips). Remove the pan from the heat (take care it will be very hot) and add the chopped almonds to the caramel. Stir once and pour onto the greased baking sheet. Leave for 30 minutes until set.
Transfer the praline to a chopping board and roughly break up with the end of a rolling pin. Reserving 12 shards, place the remaining praline into a food processor and whizz to fine crumbs. Spread on a flat plate.
Remove the cake rounds from the freezer. Sandwich the rounds together in pairs with a little of the coffee icing and 1/2 teaspoon of the praline to make 12 mini cakes. Use a small palette knife to spread a thin layer of coffee icing around the sides of each mini cake, then roll each cake in the crushed praline to coat the sides completely.
Use the remaining coffee icing to decorate the top of the cakes, swirling with the tip of the palette knife. Decorate each cake with one of the reserved caramel almond shards and any leftover praline crumbs, if liked. Serve immediately or store in an airtight container in a cool place for up to 1 day.