Step 1Make the cake: Heat oven to 350 degrees. Grease an 8-inch round springform pan with coconut oil. Line the bottom with parchment paper and grease the parchment.
Step 2Melt the coconut oil and 1 1/2 cups chocolate chips together, either by stirring in a saucepan over low heat until smooth or microwaving in a large microwave-safe bowl in 30-second increments, stirring between each until smooth, about 1 ½ minutes.
Step 3Whisk in the sugar, vanilla and salt until incorporated, then whisk in the eggs until smooth. Whisk in the cocoa powder until just combined. Pour the batter into the prepared pan and smooth the top with a spatula. Bake until the cake forms a thin crust on top and the center is still slightly jiggly, 24 to 25 minutes.
Step 4Cool the cake on a wire rack for 10 minutes. If the edges seem stuck, loosen with an offset spatula or dull knife. Release the sides of the pan and remove. Cool completely on the base on a wire rack.
Step 5While the cake cools, make the topping: Melt the remaining 1 cup chocolate chips and the coconut milk together either by stirring in a saucepan over low heat until smooth or microwaving in a large microwave-safe bowl in 30 second increments, stirring between each until smooth, about 1 minute.
Step 6Slide the cooled cake off the parchment on the base and directly onto the rack. Set the rack over a rimmed baking sheet. Pour the warm ganache over the center of the cake. Using a spatula, gently spread it out to the edges, letting it drip evenly down the sides. Smooth the sides and decoratively swirl the top, if desired. Refrigerate the cake, uncovered, until the ganache sets, 1 ½ to 2 hours. Sprinkle the toasted coconut flakes on top before serving.