Preheat oven to 325°F. Place cream in heavy medium saucepan. Scrape in seeds from vanilla bean; add bean. Bring to simmer over medium heat. Whisk yolks and 1/2 cup sugar in medium metal bowl to blend. Set bowl over saucepan of simmering water (do not allow bowl to touch water). Whisk vigorously until yolk mixture is pale yellow and hot to touch, about 3 minutes. Gradually whisk in hot cream mixture; discard vanilla bean.
Divide cream mixture among six 3/4-cup soufflé dishes or custard cups. Arrange dishes in 13x9x2-inch baking pan. Pour enough hot water into pan to come halfway up sides of dishes. Bake custards until almost set in center and light golden on top, about 35 minutes. Remove custards from water; refrigerate overnight.
Preheat broiler. Sprinkle 1 teaspoon sugar atop each custard. Place dishes on small baking sheet. Broil until sugar just starts to caramelize, rotating sheet for even browning, about 2 minutes. Refrigerate custards until topping hardens, at least 30 minutes and up to 3 hours.
Meanwhile, toss berries, brown sugar, and raspberry liqueur, if desired, in large bowl. Spoon berry mixture atop custards and serve immediately.