1. Bring milk and sugar to simmer in medium saucepan over medium heat. Add corn kernels. Simmer until corn is tender, about 5 minutes. Strain milk into large saucepan; add 2 cups cream, coarse salt, and corn cobs. Bring to simmer. Cover; remove from heat. Steep 30 minutes. Transfer corn to small bowl. Cover; chill.
2. Meanwhile, place 3 tablespoons water in small cup. Sprinkle gelatin over. Let stand until gelatin softens, at least 15 minutes.
3. Remove cobs from cream mixture; discard cobs. Bring cream mixture to simmer. Remove from heat. Add softened gelatin; stir to dissolve. Divide cream mixture among six 3/4-cup ramekins or custard cups. Cover and refrigerate until set, at least 6 hours and up to 1 day.
4. Whisk dulce de leche and 3 tablespoons cream in small bowl to blend. Spoon some sauce over each panna cotta. Sprinkle a few corn kernels over each dessert (reserve remaining corn for another use) and serve.