Bring the milk, rice, cinnamon, and salt to a boil in a large, heavy-bottomed saucepot over medium-high heat.
Reduce heat to medium-low and simmer (uncovered) stirring frequently and scraping the bottom of the pot to ensure the rice isn't sticking, for about 20 minutes, or until the rice is tender.
Split the vanilla bean in half lengthwise, scrape out the seeds and add them to the pot, along with the scraped pod and 1 cup sugar. Simmer, stirring, until slightly thickened, 5 to 7 minutes.
Remove saucepot from the heat, take out the vanilla bean pod and transfer the rice pudding to an oven-safe dish (or dishes). Let cool 20 minutes.
Sprinkle rice pudding with remaining 3 tablespoons sugar and place under broiler until sugar has caramelized and formed a hard shell (See Notes).
Watch the sugar carefully and rotate the dish (or dishes) to ensure even caramelization.
Top with fresh berries and serve immediately.
The pudding will thicken as it cools, so ideally it should be a bit thinner than you want when you stop cooking it.
The easiest way to broil without burning yourself is to place the dish on a sheet tray so that you're rotating the larger sheet tray rather than a smaller dish.
A thin, even layer of sugar atop the pudding is critical for perfect caramelization. After you sprinkle it atop the pudding, shake it around the dish and carefully pour out the excess.