Preheat oven to 350° F. Grease a 12-cup bundt pan and dust it with unsweetened cocoa powder.
Place chocolate in a double boiler and melt over medium-low heat, stirring occasionally, until melted and smooth. Set aside.
Combine flour, cocoa, baking soda, and salt in a bowl and set aside. Pour Kahlua into a 2-cup glass measure with a pour spout. Spoon in sour cream until the Kahlua and sour cream reach the 2-cup line. Mix well and set aside.
In the bowl of a standing electric mixer, cream together butter and brown sugar until light and fluffy.
Add the eggs to the butter mixture one at a time, beating well after each addition. Beat until well blended. Add the vanilla and melted chocolate and stir to mix.
Add the flour mixture, alternating with the sour cream-Kahlua mixture, to the egg-butter mixture. Stir until the dry ingredients are just moist and blended. Do not over mix.
Stir in boiling water and mix until blended. Gently stir in chocolate chips.
Scrape the batter into prepared bundt pan, smoothing the top to even out the batter. Bake for 55 to 60 minutes, until the cake is firm to the touch and a skewer inserted into the center comes out with just a few crumbs clinging to it.
Remove from the oven and cool the cake for 30 minutes in the pan. Carefully turn the cake out onto a rack and cool completely.
For the glaze, place dark chocolate in a 2-cup measuring glass with a pour spout. Bring cream to a boil in a small saucepan over medium heat. Pour cream over the chocolate and let it sit without stirring for two minutes before mixing vigorously with a small spatula. Once the chocolate becomes smooth and glossy, add 1 tablespoon Kahlua and mix until smooth.
Set the rack holding the cooled cake atop a baking sheet. Stir the ganache well before slowly drizzling the glaze over the cake. Allow the glaze to set for about 10 minutes before slicing.
Serve cake slices at room temperature with scoops of vanilla ice cream, if desired.