Preheat your oven to 325°F (160°C). Arrange four 6-ounce ramekins in a deep baking dish or roasting pan.

In a small bowl, whisk the matcha powder with about 2 tablespoons of the heavy cream to create a smooth, lump-free paste.

In a medium saucepan, heat the remaining heavy cream over medium heat until it begins to steam and bubble slightly at the edges. Remove from heat immediately.

Stir the chopped white chocolate and the matcha paste into the hot cream until fully melted and combined.

In a separate mixing bowl, whisk the egg yolks, 1/4 cup sugar, vanilla extract, and salt until the mixture is pale and slightly thickened.

Slowly pour the hot cream mixture into the egg yolks in a thin stream, whisking constantly to temper the eggs so they don't scramble.

Strain the custard mixture through a fine-mesh sieve into a pouring pitcher to remove any air bubbles or cooked egg bits.

Pour the custard evenly into the prepared ramekins. Carefully pour boiling water into the baking dish (around the ramekins) until it reaches halfway up the sides of the ramekins.

Bake for 35 to 40 minutes, or until the edges are set but the centers still jiggle slightly like gelatin when shaken gently.

Remove the ramekins from the water bath and cool to room temperature. Cover and refrigerate for at least 4 hours or overnight.

Just before serving, sprinkle 1 tablespoon of sugar evenly over the top of each custard. Use a kitchen torch to melt and caramelize the sugar until it forms a hard, amber crust.