I first made this recipe because the idea of baked vanilla custard gave me tingles. It's such a luxurious-sounding dessert. I adore a rustic scoop of pudding for dessert and I have found that simple presentations like these always get devoured completely at dinner parties. You could serve this custard with a plate of cookies or ladyfingers for textural contrast.
Position a rack in the center of your oven and preheat the oven to 350 degrees F. Have a 2-quart oval baking dish and a roasting pan large enough to hold the baking dish ready.
Prepare the berries: Combine the strawberries, cherries, sugar and salt in a small saucepan. Cook over medium heat without stirring, until the fruit has softened a bit and released lots of juices, about 5 minutes. Transfer the fruit and a scant 1/4 cup (59 milliliters) of the juices to the baking dish. Discard any remaining juice.
Make the custard: Combine the sugar and egg yolks in a large mixing bowl and beat vigorously with a whisk until very light and creamy looking. Add the mascarpone and beat just until combined; set aside.
In the bowl of an electric mixer fitted with the whisk attachment, whisk the cream and vanilla on medium speed to soft peaks, about 3 minutes. Gently fold the cream and vanilla into the mascarpone mixture until no streaks remain.
Carefully dollop the custard on top of the berries. Place the baking dish in the roasting pan and place the roasting pan in the oven. Pour hot but not boiling water into the roasting pan so it comes two-thirds of the way up the sides of the baking dish.
Bake for 1 to 1 1/2 hours, until the surface is lightly golden, the edges are set and the center is slightly jiggly. If it starts getting too dark too quickly, cover with foil.
Remove the pudding from the roasting pan and let it cool to room temperature on a wire rack. Cover the custard and chill for 6 hours or overnight. Serve chilled, topped with a dusting of confectioners' sugar and sliced strawberries.