It isn't a molten chocolate cake, it's just really soft and spongy, and the center has an ooey gooey filling. The batter is made with cocoa powder and chopped bittersweet chocolate chunks are folded in. It's a chocolate lover's dream. The vanilla sauce is a nice addition, because it soaks perfectly in to the cake, and it makes the cake a little less rich. It tastes best when the cake and the sauce are served warm, but it's perfect any way you can get it.
First cut off small strips of aluminum foil that will fit as strips in a mini loaf pan, as shown below. You want the foil to stick out, this will make it easy to remove them, since you will only bake them 3/4 of the way, and if you don't do this they won't come out cleanly. Now with the foil in all the molds spray the pan to grease it.
In a small mixing bowl add the dry ingredients:
1 1/2C all purpose flour
1/2t baking powder
1/2C cocoa powder
sift these over aluminum foil. Set aside, you will mix these in to the batter at the end.
In a large mixing bowl add:
1 stick soft unsalted butter
1/4C oil
3/4C sugar
1T vanilla extract
Mix till creamy and lighter in color.
Add 2 eggs, mix
then 1/4C sour cream, mix till smooth.
Now add the dry ingredients. Mix on low till smooth and combined.
Boil 1/2C water, add this in to the batter. Mix till smooth.
Now fold in:
4oz chopped bittersweet chocolate (1 bar).
Divide the batter in to the molds. Bake for 10-12 minutes at 350F. Only bake these 3/4 of the way. If the skewer comes out clean then they were baked too long, the center must be gooey, and when you take them out to cool slightly they will continue to bake a little, so keep that in mind. Better to under bake than over bake. A good way to check is if the edges of the cake 1/2" in are baked and the skewer comes out clean on the edges, just don't wait for the center to come out clean, it shouldn't. They will look puffed up, but because the center is not baked fully it will sink a little, that is a good thing. Cool slightly. Then dust with powdered sugar. Lift out of the molds with the aluminum flaps sticking out, remove the foil and serve with vanilla sauce (recipe below).
Vanilla sauce:
In a small saucepan add:
1C whole milk
1/2C heavy cream
1/4 vanilla bean (scraped out, and add the pod, remove when serving)
Bring to a simmer.
In a small bowl add:
3 egg yolks
between 1/8-1/4C sugar. The cake is sweeter, so you don't want this to be too sweet. We prefer more around 1/8C sugar, but it is your preference. Whisk well. When the cream mixture is almost boiling, pour it in to the egg mixture slowly, whisk constantly, to prevent the eggs from cooking, you are just tempering. Now pour the whole thing back in to the saucepan, stir constantly on low heat and let it thicken. It is thick enough when it covers the back of your spatula without dripping off. Pour in to a glass to prevent it from cooking further and serve with the cakes.