Begin by preheating the oven to 350°F and preparing a 9-inch springform pan by greasing it thoroughly and lining the base with parchment paper. In a large mixing bowl, beat 2 extra-large eggs with 6 tbsps (75g) granulated sugar until the mixture becomes thick and pale.
Gently fold in the sifted ⅓ cup (55g) all-purpose flour, ½ tsp baking powder, and ¼ tsp salt, taking care not to deflate the mixture.
Pour the batter into the prepared pan, spread it evenly, and bake for 20–25 minutes until the sponge is springy to the touch. Remove from the oven and allow it to cool completely before carefully cutting the sponge horizontally in half.
Once the sponge has cooled, clean the springform pan and re-line it with fresh parchment. Place one sponge layer inside the pan to form the base.
Prepare the cheesecake filling by beating together ½ cup (115g) softened salted butter, ¾ cup (150g) granulated sugar, 3 egg yolks (reserving the whites), finely grated zest and juice of 2 oranges, and ¾ cup + 2 tbsps (200g) full-fat cream cheese until smooth and well combined.
In a separate bowl, whip 1¼ cups (300ml) heavy cream until it reaches a light, cloud-like consistency, then gently fold this into the cheese mixture.
Whip the 3 reserved egg whites until stiff peaks form and carefully fold them into the filling until just combined. Pour half of the cheesecake mixture over the first sponge layer, top with the second sponge layer, then add the remaining filling, smoothing the top evenly.
Refrigerate the cheesecake for several hours or overnight until set. Before serving, dust the top with confectioners' sugar and decorate with fresh orange segments and mint leaves for an elegant presentation.