For the Almond Espresso Crust:

1. In a food processor, process the almonds, buckwheat, activated oat flour, mesquite powder, coconut sugar and espresso powder (if using) together until a coarse flour forms. Do not overprocess these ingredients since texture should be present in the crust. Add the melted coconut oil, almond butter and vanilla, and process again until the mixture starts sticking together.
2. Line two 4 1/2-inch (11.5-cm) springform pans with parchment paper or plastic wrap on only the removable bottom. Press the crust mixture firmly into the bottom of each pan with your fingers and use the back of a little spoon to even out the crust. Set aside at room temperature while you make the chocolate espresso filling.

For the Chocolate Espresso Filling:

1. Before starting the filling, have some white chocolate sauce prepared and ready to use for the next step. In a high-speed blender, blend together the cashews, coffee, cacao powder, coconut nectar, lemon juice, sunflower lecithin, vanilla and salt until combined and smooth. The mixture will be very thick, but it will thin out once you add the cacao butter. Add the melted cacao butter and blend on low speed for a few seconds until well incorporated.

For the Assembly: 

1. Pour the chocolate espresso filling into each cake pan, filling them to the top. Transfer the white chocolate sauce to a squeeze bottle or piping bag, and on top of the filling, create dots in a circular pattern, starting from the middle, working your way to the outer edges. Using a toothpick or wooden skewer, only grazing the top, create a marbled effect.
2. In a blender, blitz the cacao nibs to create smaller pieces and place them on the outside edges of the cakes for decoration. Chill the cakes in the freezer for a minimum of 8 hours or overnight, until firm. The cakes need to be frozen to smoothly remove them from the springform pans. Remove the pans from the freezer and remove each cake from its springform pan while still frozen. Allow the cakes to thaw for about 30 minutes at room temperature before slicing. Serve immediately or store in the fridge for 5 days or in the freezer for up to 1 month.