In a glass bowl set over a pot of simmering water, melt together 16 oz. bittersweet chocolate and unsalted butter. Stir until just smooth and set aside.

Heat heavy cream and corn syrup over medium heat until bubbles just begin to form along the sides of the pan. Quickly pour over melted chocolate and stir a few times to incorporate. Let sit for 2-3 minutes and stir until mixture is smooth.

Add brandy and coffee liqueur and stir to incorporate. Pour into glass baking dish and refrigerate 1 hour to set.

Using a melonballer, scoop chocolate mixture and roll into 1-inch spheres. Place on a parchment sheet and refrigerate another 1 hour.

Melt remaining 8 oz. bittersweet chocolate in a glass bowl over simmering water until smooth. Allow chocolate to cool to about 92-93F. Using two regular teaspoons, roll truffles in melted chocolate until fully covered. Tap on edge of bowl to release any extra chocolate from around truffle.

For cocoa powder truffles: add chocolate dipped truffle to bowl of cocoa powder and gently roll to coat. Tap to release excess powder and set on parchment paper lined baking sheet to set.

For pistachio truffles: place chocolate dipped truffles on parchment paper lined baking sheet and quickly sprinkle with chopped pistachios.

Let truffles set with chocolate at room temperature for another 1 hour. Store in an airtight container at room temperature.