1. Heat oven to 325 degrees F. Arrange rack in center of oven.
2. Melt 1/2 cup sugar in a small saucepan over medium heat, swirling pan occasionally, until sugar becomes amber in color, 10 minutes (do not stir). Pour caramel into the bottom of a 4- or 5-cup souffle dish.
3. Bring milk, cream, remaining 3/4 cup sugar and cinnamon stick to boil in a small saucepan over medium heat. Remove from heat; cover and let stand 10 minutes.
4. Meanwhile, whisk together eggs, vanilla and salt in a large bowl. Strain milk mixture through a sieve into eggs; whisk to combine. Discard cinnamon stick. Strain mixture again into prepared dish. Place dish in a roasting pan, making sure there is at least 1 inch of space between the edge of the dish and the roasting pan. Place roasting pan on oven rack. Carefully pour enough hot water into roasting pan to come halfway up side of dish.
5. Bake until custard is just set, 60 to 65 minutes (mixture will jiggle slightly, but thats okay). Remove flan from oven. Let flan cool in hot-water bath 15 minutes. Remove dish from water bath and cool completely on wire rack. Cover with plastic wrap and refrigerate overnight.
6. To serve, run a knife around the edge of souffle dish. Place a serving plate slightly larger than dish on top. Invert flan onto plate.