Start this recipe a day ahead so that you have a chance to thoroughly chill the salted caramel sauce. Place the sugar and water in a medium saucepan and gently swirl the pan to ensure all of the sugar is covered with the water. Place the saucepan over a medium heat and simmer until the sugar turns a chestnut brown colour. Add the butter or coconut oil and stir until the butter is melted and incorporated into the sugar. Now carefully add the cream. Be careful with this step as the sauce will bubble violently, so add the cream slowly. Stir well and allow the mixture to bubble and boil for a further minute. Remove from the heat and stir in the flaked sea salt. Leave to cool for 20 minutes before pouring into a glass jar and refrigerating overnight.
Prepare the Chocolate Fondant Cakes
Preheat the oven to 400 degrees Fahrenheit (200 Celsius) and place a baking tray inside the oven. Grease 2 dariole molds well. I like to do this with a couple of layers of butter or coconut oil, and chilling in the fridge in between each layer. Coat the inside of each mold with 1/2 tsp of cocoa.
To make the fondants begin by melting the chocolate and butter (or coconut oil, if using). You can do this by placing a heatproof bowl over a pan of gently simmering water or in the microwave in 20 seconds bursts, stirring each time.
Place the egg, yolk and sugar in a bowl and whisk well to combine. Add the chocolate mixture along with the flour and stir until well mixed.
Fill the darioles with half the mixture. Then remove the caramel from the fridge. By this time it should be firm and pliable. Scoop out 1 1/2 tbsp of the sauce and roll it into a ball and place it in the center of the chocolate mixture, making sure it doesn't touch the sides. Top with the remaining chocolate mixture.
Place the fondants in the oven, on top of the baking tray, and bake for 10 minutes. The top of the fondants will turn a glossy matte. If the center still appears glossy bake for a further minute or two until it looks matte. Remove and let them sit for 3 to 4 minutes before removing from the moulds. They should come out of the darioles fairly easily, assuming they are well greased, but if they don't use a palette knife and run it carefully along the inside of the mold before turning upside down onto a serving plate.
Serve dusted with cocoa powder and your favorite ice cream or cream.