Set up your grill for indirect heat. If using a charcoal grill, build the coals on one side only. If using a gas grill, heat one side only.
For the miso chocolate cake: Prepare a 9-inch cake pan by spraying it with cooking spray, laying a parchment circle on the bottom and spraying it with cooking spray again.
In a stand mixer fitted with the paddle attachment, cream the sugar, coconut oil and miso until smooth and no longer grainy. Add the eggs to a small bowl, pour the vanilla extract into the eggs and then add to the stand mixer. Mix until smooth, scraping the sides and bottom of the bowl. Alternatively, use a hand mixer or just whisk by hand.
In a separate mixing bowl, whisk together the flour, cocoa powder, baking powder and baking soda. Add to the mixer and mix until just combined, then add the buttermilk. Mix until incorporated. With the mixer on low, carefully add the boiling water to the cake batter until well combined. Pour the cake batter into the prepared pan. Pick up and tap down to let out any air bubbles.
Place the cake on the indirect side of the gill, close the lid and bake until a toothpick inserted into the center comes out clean, about 45 minutes. Let cool slightly before flipping it out of the pan and onto a serving platter.
For the coconut whipped cream: Open the refrigerated cans of coconut milk. Scoop the coconut cream off of the top (totaling 3/4 cup) and add to the bowl of a stand mixer fitted with the whisk attachment. Add the honey and vanilla and whip until light and airy, about 5 minutes.
Once the cake is cool, spread the coconut cream on top and sprinkle with toasted coconut before serving.
To bake in the oven, bake at 350 degrees F until a toothpick inserted in the center of the cake comes out clean, 45 to 55 minutes.