Before you start, preheat oven to 180°C.
Combine all mousse ingredients together in a blender and blend for about 1 minute, until smooth and mousse-like in consistency. Transfer to a bowl, cover and place in the fridge for about 1 hour to set.
Place macadamias, almonds, hazelnuts and coconut thread in a blender and pulse a couple of times, until nuts have been roughly chopped. Melt coconut oil in a large heat-proof bowl in the microwave. Once melted, add maple syrup, vanilla and salt. Add nuts and toss to coat.
Transfer mixture to a lined oven tray and bake for 10-15 minutes, until golden brown. Remove from oven and cool completely.
Serve mousse with nutty crumb.