Grease a 9x9” pan with butter. Arrange the croissant pieces in the pan.
In a large bowl, whisk the eggs.
Then, whisk in the brown sugar and granulated sugar.
Next, whisk in melted butter, milk, cream, vanilla and sea salt until combined.
Pour custard mixture over the croissants in the baking dish.
Gently press the croissants down with a spatula until every piece is absorbing the liquid.
Bake, uncovered, in the preheated oven for 40-45 minutes, until the top is set and springs back lightly when pressed, a cake tester inserted in the center comes out clean or the internal temperature of the pudding is 165 degrees F.
Let cool for at least 30 to 60 minutes, then serve warm