In a saucepan, combine milk, cream, sugar, vanilla and orange zest. Let this simmer for about half an hour.
Cut the crust off your brioche and then cut into large cubes.
Strain the cream mixture and split this into two.
Pour half of the cream mixture over the brioche. Cover and let soak for at least an hour in the fridge (the longer the soak, the more custard-like it will be).
With the other half of the cream mixture, slowly incorporate this into 2 egg yolks that have been lightly beaten. Do this in a few stages to not scramble your eggs if the mixture is still hot.
Place the cream and egg mixture back on the stove, on very low heat. Using a spatula, move in a figure eight motion to move the custard so you do not scramble it. The custard is ready when you can coat the back of a spoon and place a line through it. Let the custard cool completely.
Take out the bread and dip into the custard.
Place a non-stick pan on the stove with a small amount of butter for each piece of bread. Sear until golden brown on all sides.
Place on a plate and sprinkle a bit of sugar on top.
Serve with some ice cream and enjoy a traditional taste of Spain.