01 - Preheat the oven to 425°F. Generously butter four 6-oz ramekins and dust with flour, tapping out excess.
02 - Sift together the matcha powder, flour, and salt in a small bowl.
03 - In a heatproof bowl, melt the butter and white chocolate over a saucepan of simmering water, stirring until smooth. Let cool slightly.
04 - In a separate bowl, whisk together eggs, egg yolks, and sugar until thick, pale, and slightly foamy (about 2 minutes).
05 - Stir the melted chocolate mixture and vanilla extract into the egg mixture until well combined.
06 - Gently fold in the dry ingredients, mixing just until no streaks remain. Do not overmix.
07 - Divide the batter evenly among the prepared ramekins.
08 - Place ramekins on a baking sheet and bake for 11–13 minutes, until the edges are set but centers are still soft.
09 - Let cool for 1 minute, then run a knife around the edges and invert each cake onto a plate. Dust with powdered sugar and serve immediately, optionally with fresh berries.