1. Melt the chocolate. Add the coconut oil and sunflower oil and mix well. In one bowl, combine the coffee, milk, vanilla, salt, and sugar, and mix. In another bowl, place the flour, baking powder, and cornstarch.
2. Add the oil/chocolate mixture and the remaining wet ingredients to the bowl with the dry ingredients and mix for 2 to 3 minutes.
3. Finally, add the walnuts and mix well with a spatula. Transfer the mixture to a 24cm square baking pan and bake at 150°C for 35-40 minutes.
