For the crust: spray 10" tart pan with removable bottom with cooking spray.
Mix flour, sugar, cocoa powder and salt in a food processor.
Add butter to flour mixture and process until the mixture resembles wet sand.
Add ice-cold water to the mixture and blend until dough comes together in a ball.
Press dough into a prepared tart pan. Chill at least an hour, or overnight.
Bake the crust in 350oF oven until dry, about 20 minutes. Cool completely.
For filling: in a medium sauce pan mix brown sugar, cream, maple syrup and ginger, set over medium-high heat and boil, whisking gently, until sugar dissolves and begins to bubble vigorously, about 8-10 minutes. Mix in cashews and coconut. Cool to room temperature.
Chop chocolate and warm it up in the microwave until it begins to melt. Take it out of the microwave, stir with a wooden spoon until it melts completely.
Brush melted chocolate on the inside of the baked crust to coat completely. Reserve remaining melted chocolate for garnish.
Put the coated crust into the freezer for about 5 minutes, to harden the chocolate.
Pour filling into the chocolate-coated crust. Bake the tart in 350oC oven for about 35 minutes or until the filling begins to darken and bubbles thickly.
Transfer tart to a cooling rack and cool completely. Remove the tart from the pan.
Remelt reserved chocolate in microwave and drizzle it over the tart in a lacy pattern.
Store tart at room temperature covered with the cake dome.