Créme Renversée is a fancy term for créme caramel, the classic French dessert that combines a silky smooth custard with a drizzle of caramel syrup. Here we've added both fresh and crystallized ginger to the mixture, which imparts texture and flavor to what can otherwise be a rather bland dessert. If you're a purist, however, the recipe will work without the heat and crunch of the ginger.
Make the caramel by combining the sugar and water in a small saucepan set over medium-high heat. Cook, stirring frequently, until the sugar dissolves. Raise the heat to high and boil the syrup until it turns golden brown in color. Remove the pan from the heat and divide the caramel among six 6-ounce ramekins, tilting to coat the bottom and sides of the ramekins. Set aside at room temperature.
Place the milk, vanilla bean, and ginger slices in a small saucepan and bring to the start of a boil. Remove the pan from the heat, cover with a lid, and let the mixture steep for 15 minutes to infuse the milk with the flavor of the vanilla and ginger. After 15 minutes, remove the vanilla bean and ginger slices from the milk. Discard the ginger; wash and dry the vanilla bean and save for a future use, if desired.
Position a rack in the lower third of the oven and preheat to 300 degrees F.
In a medium-size bowl, whisk the eggs, egg yolks, sugar, and salt until just combined. Pour in half of the warm milk, whisking gently. Don't overmix the custard or it will foam. Add the remaining milk, stirring gently. Skim off any foam.
Divide the custard among the prepared ramekins. Place the ramekins in a roasting pan and add hot water to come half way up the sides of the dishes. Cover with a sheet of aluminum foil and carefully transfer the pan to the preheated oven. Bake until the custard is just set and the tip of a knife inserted into the center of the custard comes out clean, about 1 hour.
Remove the roasting pan from the oven and transfer the ramekins with tongs to a wire rack to cool. When cool, refrigerate the ramekins at least 6 hours before serving.
To serve, run a hot, thin knife around the edges of each custard, one at a time. Place a serving plate over each ramekin and invert. Leave the ramekins inverted for several minutes so that most of the caramel will melt onto the custards. Garnish each serving with a dollop of whipped cream sprinkled with a tablespoon of the crystallized ginger, if desired.