Step 1

Preheat your oven to 350°F. Grease and line an 8-inch round or square baking pan. Set the pan aside.

Step 2

In a medium-size, heat-safe mixing bowl or measuring cup, place the boiling water and brewed coffee and the cocoa powder, and whisk until well-combined. The cocoa powder will resist combining, so just keep whisking.

Step 3

Add the (optional) chopped chocolate, and mix until melted and smooth. Add the mayonnaise, sugar, salt, and vanilla, and whisk until well-combined.

Step 4

In a large bowl, place the flour, xanthan gum, cornstarch, baking soda, and about 5 ounces of the (optional) chocolate chips, and mix to combine and coat the chips in the flour.

Step 5

Create a well in the center of the dry ingredients, and add the wet mixture. Mix until very smooth and well-combined. The batter will start off very thin, but will thicken a bit as you stir. Keep mixing until that happens.

Step 6

Transfer the cake batter to the prepared pan, and smooth into an even layer using a moistened spatula or broad, flat knife.

Step 7

Sprinkle the remaining (optional) chocolate chips evenly over the top, and bang the cake a few times on the counter to help the chips adhere.

Step 8

Place the pan in the center of the preheated oven and bake for about 30 minutes, or until done.

Step 9

Doneness should be determined by a few things: the cake should be puffed and rounded at the edges. It also shouldn’t jiggle when moved back and forth, and a toothpick inserted in the center should come out mostly clean (and certainly not wet).

Step 10

Remove the cake from the oven, place the pan on a wire rack and allow to cool completely in the pan. To make it easier to slice, you can chill the pan in the refrigerator.

Step 11

Place the chopped dark chocolate in a small, heat-safe bowl.

Step 12

Place the coconut cream in a small, heavy-bottom saucepan and melt over a low flame. Pour the hot cream over the chopped chocolate.

Step 13

Allow the chocolate and hot cream to sit, undisturbed, for about 5 minutes before whisking until completely smooth.

Step 14

Pour the glaze directly over the cooled cake, and allow it to set at room temperature.

Step 15

To whip the chocolate ganache into frosting, allow it to cool at room temperature, then cover and refrigerate it until beginning to set (about 20 minutes).

Step 16

Using a handheld mixer or a stand mixer fitted with the whisk attachment, whip the frosting until lighter in color and relatively fluffy (about 3 minutes).

Step 17

Frost the cakes as desired, then slice and serve.