Cut vanilla bean in half lengthwise; scrape seeds into a 2- to 3-quart pan. Add vanilla pod, cream, and milk. Stir occasionally over medium-high heat until mixture just begins to boil, 14 to 18 minutes.
Meanwhile, in a bowl, whisk together egg yolks and sugar. Place chocolate in a small, microwave-safe glass bowl and heat in a microwave oven at half-power (50%) until soft, 1 1/2 to 2 minutes. Stir chocolate until smooth.
Lift vanilla pod from cream mixture; rinse and dry for another use or discard. Whisk about 1/2 cup of the hot cream mixture into egg mixture, then whisk egg mixture into remaining cream mixture. Add hot melted chocolate (if it has cooled to room temperature, reheat briefly in microwave oven just until hot to touch; do not overheat). Pour mixture into a blender and whirl until no chocolate flecks remain. Pour through a fine strainer into a 1- to 2-quart glass measure. Stir in Amaretto and Kahlúa.
Set six to eight soufflé cups, ramekins, or teacups (1/2 to 3/4 cup) in a 9- by 13-inch baking pan. Fill cups equally with chocolate mixture. Set pan in a 300° regular or convection oven and carefully pour about 1 inch of boiling water into pan around cups.
Bake until centers of custards barely jiggle when pan is gently shaken, 30 to 35 minutes. With a slotted spatula, lift cups out. Chill until custards are cold, 1 to 1 1/4 hours (see notes).
Garnish each crème brûlée with a large chunk of chocolate praline. Serve any remaining praline alongside.
Notes: Karen Krasne, creator of Extraordinary Desserts in San Diego, stretches the definition of crème brûlée with this dark chocolate custard capped with a chunk of crisp chocolate praline. The custard can be made through step 5 up to 2 days ahead; cover and chill.