In a food processor, process the macadamia nuts, rolled oats, shredded coconut and salt together until the mixture resembles a crumble. Add the agave, tahini, lime zest and vanilla, and process again until combined. Do not overprocess the mixture; it should retain a crumble consistency.

Spread the crumble on a lined dehydrator tray and dehydrate at 115°F (46°C) for 16 to 18 hours, or until fully dry. Transfer the crumble to the freezer to crisp up until ready to use.

In a food processor, process the macadamia nuts, rolled oats, shredded coconut and salt together until the mixture resembles coarse flour. Add the agave, tahini, melted coconut oil, lime zest and vanilla, and process again until the batter sticks together. Do not overprocess, since the macadamia nuts will release oil very quickly.

Line an 8-inch (20-cm) square baking pan with parchment paper and, using your hands, press the crust batter into the bottom of the pan to create an even, thick layer. Using the back of a spoon, firmly smooth out the layer. Set the crust aside at room temperature while you make the tropical cream.

In a high-speed blender, blend together the mango, pineapple, coconut meat, coconut butter, agave, lemon juice, sunflower lecithin and salt until smooth. Addthe melted coconut oil and blend again until combined. Pour the tropical cream filling on top of the crust and pat the pan on the counter to even out the layer and remove any air bubbles.

Remove the crumble from the freezer; if the pieces are large, blitz the crumble in a food processor until broken down. Add the crumble evenly as a layer on top of the tropical cream filling, pressing the crumble into the cream so the crumble sets in the filling.

Chill the pan in the freezer for a minimum of 6 hours to set. Remove from the freezer and slice into 2-inch (5-cm) squares. Serve immediately or store in the freezer for up to 1 month or the fridge for up to 3 days.