Arrange berries in a shallow baking dish. Top with the sugar and salt. Gently toss to combine; set aside.

If making individual gratins: Line rimmed baking sheet with aluminum foil. Toss berries, sugar, and salt together in bowl. Divide berry mixture evenly among 4 shallow 6-ounce gratin dishes set on prepared sheet; set aside.

Whisk the egg yolks, 2 tablespoons plus 1 teaspoon granulated sugar, and wine together in medium heatproof bowl until the sugar has dissolved, about 1 minute. Set the bowl over saucepan of barely simmering water and cook, whisking constantly, until the mixture is frothy. Continue to cook, whisking constantly, until the mixture is slightly thickened, creamy, and glossy, 5 to 10 minutes (when done, the mixture will form loose mounds when dripped from the whisk). Remove the bowl from the saucepan and whisk constantly for another 30 seconds to cool slightly. Transfer the bowl to the refrigerator and chill until the egg mixture is completely cool, about 10 minutes.

Meanwhile, adjust the oven rack 6 inches from broiler element and preheat broiler. Combine brown sugar and remaining 2 teaspoons granulated sugar in a small bowl.

Whisk the heavy cream in a small bowl until it holds soft peaks, 30 to 90 seconds. Using a rubber spatula, gently fold whipped cream into the cooled egg mixture. Spoon the zabaglione over the berries and sprinkle the sugar mixture evenly on top. Let sit at room temperature for 10 minutes, until the sugar dissolves.

Broil the gratin until the sugar is bubbly and caramelized, 2 to 4 minutes. Keep a constant watch on the progress to prevent overbrowning. Serve immediately.