Line a cookie sheet with parchment or wax paper. Microwave the chopped bittersweet chocolate in a glass bowl or measuring cup at full power for one minute. Remove from microwave and stir until chocolate is completely melted and smooth. Set aside.
Place the softened cream cheese in a bowl and beat with an electric mixer at high speed until smooth, about 15 seconds. Add the melted chocolate and beat again until well incorporated, stopping to scrape down the sides with a spatula. Add 1/4 cup of the cocoa powder along with the pumpkin pie spice, rum, vanilla and 1 cup of the confectioners’ sugar. Stir until well blended. Mix in the remaining 3/4 cup of sugar. The mixture should be quite stiff.
Sift the rest of the cocoa powder into a small shallow bowl. Form 1″ balls from the truffle mixture and roll them in the cocoa powder to coat the outside. Place the truffles on the lined cookie sheet and refrigerate until well chilled. Keep refrigerated in an air-tight container.