Preheat oven to 180degC/355 Fahrenheit. Lightly grease and line the bottom and sides of a square baking tin (20cm x 20cm) with baking paper.
Place oats/ground almonds, coconut thread, cocoa powder, medjool dates, almonds and salt in a food processor and blitz until a fine, crumbly texture. Drizzle in melted coconut oil/butter and pulse until well combined and the mixture holds together when you pinch it between your fingers.
Press mixture into the prepared baking tin, pressing down firmly with the back of a spoon or spatula. Bake for 10-15 minutes until light golden. Set aside in the fridge to cool while you make the caramel.
To make the caramel, place dates and water in a medium-size pot and boil, stirring frequently, until the dates are very soft and mushed up, and all the water has evaporated. Place dates in the food processor along with the softened cashew nuts, maple syrup, coconut oil/butter and vanilla. Blitz until nice and smooth – this will take at least a few minutes. scrape down the sides of the food processor a few times to make sure everything has been blended.
Spread caramel all over the base in the baking tin. Set aside in the fridge to set for at least 4 hours or the freezer for at least 2 hours, or until the filling is firm.
Melt chocolate in the top of a double boiler or in a glass bowl set above a small pot of simmering water. Mix in oil if using. Pour melted chocolate all over the filling and spread it over evenly. Return to the fridge for about 20 minutes, or until set. If it still seems a bit soft, return to the fridge/freezer for a bit longer.
Cut into about 25 pieces (a long, sharp serrated knife dipped in hot water will help a lot! I also find it easier to flip the whole caramel slice upside-down and cut through the base down). The slice will keep for up to a week in the fridge.
** To make softened cashew nuts, either soak in water overnight, or boil cashew nuts in a pot of water for about 15 minutes or until soft. Drain.