In a large bowl, whisk together eggs, milk, vanilla, lemon juice and lemon zest until combined. In a separate bowl, combine all the cinnamon sugar coating ingredients.
Spread lemon curd onto each slice of brioche, roughly a tbsp per slice. Put two slices together to make a sandwich and gently press together.
Working one at a time, dip the sandwich into the egg mixture. Get the egg mixture evenly coated over the bread.
Meanwhile, melt butter in a pan over medium heat. Add the dipped sandwiches into the pan and cook until it turns golden brown, around 3-5 minutes each side.
After it's cooked, roll the sandwich into the cinnamon sugar mixture until it's evenly coated.
Top with whipped cream or any other toppings you desire and serve immediately
Notes
Challah Bread can be used to substitute Brioche. Whilst regular white bread could work too, it would lack the light and tender texture compared to brioche and challan bread, as well as lacking the natural eggy & buttery touch.
When dipping bread into the egg mixture, do not leave the bread completely soaked into the mixture because that will make the bread soggy.