This is very fast, easy to make, and an impressive dessert.
You could use a full cup of whole milk, omit the crème fraîche, and bump up the flour to ½ cup if you don’t have crème fraîche on hand. I like the extra creamy texture with the moitié-moitié of milk and crème fraîche. I make my own crème fraîche and use that but sour cream works equally well.
You can make the batter ahead, fill the cast iron, and set aside. It takes about 35 to 40 minutes to bake which allows you to have it in the oven during the meal. It is nice to serve from the oven so it doesn’t need time to cool, another time saver. You’ll want to serve it warm but hey, I’ve eaten it cold and have been thoroughly satisfied. It has a soufflé-like puff straight out of the oven and is a nice presentation on the table.