Heat the oven to 350°F. Butter and flour two 12-well muffin pans.
Melt chocolate in a double boiler or a small saucepan over low heat. Set aside to cool.
In a large mixing bowl, combine all the other cake ingredients except for the eggs. Beat the mixture until it is light and fluffy.
In a medium mixing bowl, combine the cooled chocolate and the eggs. Beat together until it looks like pudding, about 2 minutes. Add this to the other ingredients and beat the mixture until it looks like whipped frosting, about 2 minutes.
Fill each well of the prepared muffin pans with 1/4 cup of the mixture (they should be filled about halfway). Bake until the cake springs back when touched and a toothpick inserted into the center comes out clean, about 20 minutes.
Cool completely on a wire rack. When cooled, run a knife along the perimeter of the cakes, invert the muffin pans, and remove the cakes.
Fill a pastry bag fitted with a medium-sized tip (or use a resealable plastic bag and cut one corner off) with Vanilla Cream. With a straw or the end of a spoon, make two or three holes in the underside of each cake. Insert the tip of the pastry bag into the opening and squeeze Vanilla Cream into the cake. When the cream floods out of the opening, it’s full. Turn the cake right side up, and place on a cooling rack fitted over a baking tray.
For the ganache:
In a small saucepan, heat the cream to a simmer. Put the chocolate into a bowl, and pour the hot cream over it. Let stand for 5 minutes. Add the butter, and stir until smooth and liquidy.
Spoon ganache on top of each cake, allowing it to pool in the center, and spread it outward with the back of a spoon. The ganache will run over the sides and dry to a smooth finish.