vegetarian
gluten freePrep the pan
Lightly grease a wide, shallow pan with unsalted butter, then sprinkle in powdered sugar and tilt the pan so it clings in a very thin, even layer. Tap out any loose sugar; too much will clump and burn before it can caramelize.
Mix the pudding base
In a saucepan, whisk together the whole milk, granulated sugar, rice flour, and starch (wheat starch or corn starch) until the mixture is completely smooth and no dry pockets remain. Scrape the bottom and corners well so the pudding cooks evenly.
Cook the pudding
Set the saucepan over medium heat and cook, whisking constantly, for about 8 to 10 minutes until the mixture thickens into a glossy pudding and ribbons off the whisk in slow trails. Keep it moving so it doesn't catch on the bottom, then cook for 1 to 2 more minutes to take off any raw starch taste.
Caramelize the pan
Set the prepared pan over low heat and let the sugar coating melt into a thin amber layer, about 3 to 5 minutes. As soon as it looks evenly caramelized and smells nutty, pour in the hot pudding and spread it quickly into an even layer with a spatula.
Chill until set
Let the pudding cool until it is no longer steaming, then refrigerate it for 2 hours until firm enough to unmold cleanly. The chill time helps the caramelized layer release in one piece.
Unmold and serve
Run a thin knife around the edges, set a serving platter on top of the pan, and flip in one confident motion so the caramelized side ends up on top. Slice into squares or wedges and serve chilled.
