In a sauce pan, combine the sugar, flour, and salt. Whisk in the orange juice, egg yolks, and lemon juice until well combined.
Cook over low heat until thick and smooth. You want it thick enough to coat a spoon.
Remove from heat and add butter. Stir until butter is melted and combined. Allow mixture to cool.
Once mixture is cool, whip cream until soft peaks form. Fold cooled orange juice mixture into the cream and refrigerate until ready to serve. This can be stored in a sealed container up to 4 days.
Preheat oven to 450 degrees.
Place butter in the skillet and heat in oven while it preheats until melted. Set aside.
In a bowl, whisk the flour, sugar, baking powder, and salt together.
In another bowl, whisk the eggs, milk, orange juice, and vanilla together until frothy.
Whisk egg mixture into flour mixture, just until combined.
Pour pancake into skillet and cook for 20 minutes until puffy and golden brown.
Remove from oven. Cut into wedges and serve topped with prepared orange custard. Serves 4.