Preheat oven to 300 degrees F (150 C). Bring a kettle of water to a boil, keep covered and sit on lowest heat to keep warm. Place eight 2.7-oz. (80ml) or four 6-oz (177-ml) ramekins (or heatproof jars) into a deep baking tray.
Add milk, cream, and ginger into a small saucepan. Cook over medium heat until almost simmering. Immediately remove the pan from the stove. Let steep for 15 minutes to allow the ginger to infuse. Remove ginger using a slotted spoon and discard. Cook the mixture again until it almost reaches a simmer.
While heating the cream mixture (after you've done infused the ginger), combine egg yolks and sugar in a medium-sized mixing bowl. Mix until the sugar is just incorporated.
Slowly pour about 1/2 cup of the heated cream mixture into the egg yolks and whisk until fully mixed. This step will bring the egg yolk toward the temperature of the hot liquid, so it won’t be cooked into solid egg when you add the rest of the cream.
Add the rest of the cream mixture while whisking, until everything is fully mixed. Pour the mixture over a strainer into a milk pan to remove any extra bits of ginger. Use a spoon to remove the foam from the surface and discard.
Pour the custard mixture into the ramekins until each of them is 80% filled.
Place the baking tray into the preheated oven. Then pour the hot water into the baking tray, until it fills half way up the height of the ramekins.
Bake until the mixture is just set, about 25 to 30 minutes. (*Footnote 1)
Remove the ramekins from the water bath using a spatula and transfer them onto a cooling rack. Let cool to room temperature, for about 1 hour. Then seal the ramekins with plastic wrap (or cover the jars with lids) and store them in the fridge for at least 1 hour, up to overnight, before serving. The custard will stay good for 3 to 4 days in the fridge, but freshly made ones taste the best.
Sprinkle 1/4 teaspoon over each chilled custard. Shake the ramekin gently so the surface is evenly covered. Light up your kitchen torch, then cook the sugar by positioning the torch at a 45-degree angle, about 6 inches (15-cm) from the sugar. Move your torch back and forth slowly so it heats up the sugar evenly and does not create any burned spots. When the sugar starts bubbling and melting and some spots turn light brown, stop the torch. The sugar will continue to cook a bit more and then set, forming a uniform golden brown crust.
If desired, garnish the creme brulees with fresh berries and serve!