Heat oven to 375°F. Grease an 8-inch round baking pan. Line bottom with a round of parchment paper and grease paper.
In a double boiler (or metal bowl set over a saucepan of simmering water) melt the chocolate and coconut oil, stirring, until smooth.
Remove from the heat and whisk in the sugar and seeds from the vanilla bean. Add the eggs and whisk until well blended. Stir in cocoa powder until just combined. Pour mixture into the prepared pan.
Bake 18 to 24 minutes, or until the top has formed a thin crust and a toothpick inserted into the center comes out mostly clean. Cool the cake in pan at least 5 minutes before removing to a serving platter. Serve with powdered sugar, sweetened cream or ice cream and fresh fruit.