For the cake: Cut a circle of parchment paper to line the bottom of an 8″ cake pan, and grease both the paper and the sides of the tin generously.  Preheat your oven to 350°.

Place the chocolate (cut into small pieces) and coconut oil in a heat proof bowl.  On the stove, add an inch of water to a saucepan and bring to a simmer over medium low heat, then place the bowl over it.  Stir and heat until the chocolate and oil have both melted, then set aside to cool.

In the bowl of a stand mixer, beat the eggs and sugar together until the eggs are pale, thick, and have almost doubled in volume.  This should take about 6-8 minutes.

Stir the cocoa powder, vanilla extract, and salt into the melted chocolate until there are no lumps of cocoa powder left, then pour the mixture into the eggs while the mixer is running on medium speed.  Beat until combined, then pour into the prepared cake  pan.  Bake for 35-40 minutes, or until the center is set.  Remove it from the oven and allow it to cool in the pan for at least 20 minutes.  The edges will pull away from the sides of the pan.  Turn it out on a cooling rack and peel away the parchment paper from the bottom.

For the Frosting: Combine all of the ingredients in a small saucepan.  Whisk to combine, and cook over medium heat, stirring constantly, until it comes to a boil.  Cook for one minute, then remove from the heat.  Continue whisking until the frosting has thickened, about 3-5 minutes, then pour over the cake and spread it out to the edges of the cake.  Work quickly, as it will thicken and become fudgy as it cools.

Chill the cake.  Top with fruit, whipped cream, or ice cream before serving.