- With the rack in the middle position, preheat the oven to 400°F (200°C). Line two baking sheets with parchment paper. On the back of the first sheet of paper, using a pencil, draw two circles with 8-inch (20 cm) diameters. On the back of the second sheet of paper, trace two long strips, each 3 inches (7.5 cm) wide.
- In a bowl, whisk the egg whites with an electric mixer until soft peaks form. Gradually add ½ cup (65 g) of the sugar and whisk until firm peaks form. Set the meringue aside.
- In another bowl, whisk the egg yolks and remaining sugar with an electric mixer until the mixture triples in volume and falls from the beaters in a ribbon, about 10 minutes.
- Using a spatula, stir one-third of the meringue into the egg yolk mixture. Gently fold in the remaining meringue.
- Sift the flour over the egg mixture and gently fold in with a whisk.
- Transfer the batter to a pastry bag fitted with a ½-inch (1 cm) plain tip. Using the traced circles as guidelines, pipe out two discs of batter, leaving a ½-inch (1 cm) space at the centre of each circle. Using the traced strips as guidelines, pipe out ladyfingers, each 3 inches (7.5 cm) long, leaving no space between the cookies. Sprinkle the cookies with some icing sugar.
- Bake one sheet at a time for 8 minutes or until a toothpick inserted in the centre of a cookie comes out clean and the cookies are slightly golden. Let cool completely.
- Using a spatula, carefully remove the cookies from the parchment paper. Set aside. It is best to make the cookies the day before assembling the charlotte to give them a chance to dry out slightly. In this case, cover them well with plastic wrap once they have cooled.
Orange Bavarian Cream
- In a small pot, sprinkle the gelatin over the orange juice. Let bloom for 5 minutes.
- Add the orange zest and ½ cup (105 g) of the sugar. Heat gently while stirring until the sugar and gelatin have dissolved. Transfer to a large bowl and let cool. Whisk in the yogurt.
- In another bowl, whisk the cream and remaining sugar with an electric mixer until firm peaks form. Gently fold the whipped cream into the yogurt mixture.
- Line the bottom of an 8-inch (20 cm) springform pan with removable bottom with parchment paper. Line the sides with a band of parchment paper. Place one cookie disc at the bottom of the pan. Trim the cookie to fit, if needed. Place the ladyfingers vertically around the side of the pan with the flat sides facing inwards. You will have a few extra cookies.
- Add half of the orange Bavarian cream to the pan (about 2 ½ cups). Cover with the second cookie disc and the remaining orange cream. Cover with plastic wrap directly on the surface of the cream. Refrigerate for 8 hours or overnight.
- When ready to serve, garnish with the orange supremes.