I was able to find Parve semi-sweet chips at Wegman's. If making for Passover, adjust as you see fit.
Use a 9 inch springform pan. Spray pan with non-stick spray. Line bottom of pan with parchment paper and wrap outside of pan with foil.
Combine 14 ounces of bittersweet chocolate with your cubed butter in a microwave safe bowl. Microwave on half power for one minute. Stir. Microwave 30 seconds at a time until chocolate and butter are almost completely melted. Stir until completely melted and incorporated. Cool.
In a medium bowl, whip egg yolks with half of the sugar (6 tablespoons) until thick and pale, about 5 minutes. Fold cooled chocolate into the yolks along with vanilla and rum.
In a separate bowl, whip the egg whites until foamy. Gradually add remaining sugar. Continue to whip to medium stiff peaks. Fold egg whites into the chocolate mixture in thirds. Pour the batter into the prepared pan.
Bake at 350 degrees for 45 - 50 minutes, until the top of the cake is puffed and cracked. Cool cake in the pan on a wire rack. The top will fall.
Pour heavy cream into a sauce pan and heat until just boiling. Remove from heat and stir in remaining pound of chocolate.
Press down gently on top of cake to make it somewhat uniformly flat. Remove sides from the pan and invert cake onto a plate with edges lined with waxed paper. Remove parchment paper from cake and ladle warm ganache over the top. Spread out to cover the sides of the torte. Let stand until set. You can then remove the waxed paper and have a drip-free plate.