Preheat oven to 300 degrees F. In a large bowl, whisk to combine egg yolks, whole egg, heavy whipping cream, 1/2 cup sugar, orange zest, orange juice and Champagne.
Divide evenly into 6 (4-ounce) ramekins. Place ramekins in a 9x13 baking dish and fill dish up to the middle of the ramekins with boiling water. Transfer to the oven and bake until custards are just set but still shake in the center slightly, about 35-40 minutes.
Remove ramekins from baking dish and cool to room temperature, then refrigerate until completely cooled and set, at least 2 hours and up to overnight.
When ready to serve, sprinkle 1 tablespoon sugar over custards and use a torch to brûlée the top until crisp and light brown. Alternatively, use the back of a metal spoon that has been heated for 2-3 minutes over a direct flame (see below), or use a broiler set to high and broil 5-6 minutes.
HOT SPOON BRULEE TECHNIQUE:
When ready to serve, top each custard with 1 tablespoon sugar, heat a spoon over a direct flame and set spoon directly onto sugar until crisp and browned.