Remove pan from heat and whisk in sweetened condensed milk and butter (mixture will bubble vigorously) until smooth. Fit pan with thermometer and return to medium-low heat. Cook, whisking constantly, until thermometer registers 240°. Remove from heat and whisk in Grand Marnier, cinnamon, cardamom, white pepper and kosher salt. Pour into prepared pan; let cool. Sprinkle caramel with pearl sugar and orange zest, cut into ¾” pieces, and wrap individually in waxed paper.