Position a rack in the middle of the oven and preheat to 325°F.

In a medium bowl, stir together the blackberries, 3 tablespoons of the sugar and the liqueur. Let stand for 15 minutes.

Divide the berries and any rendered juices among 8 ¾-cup broiler-proof serving dishes.

Meanwhile, in a large bowl, whisk together the egg yolks and the ½ cup sugar until the mixture turns a pale yellow color.

In a medium pan over moderate heat, combine the cream and salt. Bring to a boil. Gradually whisk the hot cream into the yolks. Stir in the vanilla. Divide the cream mixture among the 8 dishes, pouring it gently to mix it as little as possible with the berries.

Transfer the small dishes to a baking pan that will fit all of them inside. Add enough very hot tap water to the pan to come halfway up the sides of the dishes. Set the pan in the oven. Bake until the custards just bubble gently around the edges, about 40 minutes. They will not be firmly set. Cool the custards in the pan of water on a rack to room temperature. Cover and refrigerate at least 5 hours or up to 2 days.

If serving the crème brûlées warm, let them come just to room temperature. Position a rack about 4 inches below the heat source and preheat the broiler to 500°F. Force the brown sugar through a coarse sieve over the tops of the custards in an even, fluffy layer.

Working in batches to maintain control set the dishes under the broiler and broil until the sugar topping turns crisp and brown, about 30 seconds. Serve immediately, warning diners that the edges of the dishes will be hot.

Or, return them to the refrigerator and serve them cold, within a few hours of broiling.