Preheat oven to 425°F (218°C).
Generously butter ramekins and dust with sugar or flour. Place on a baking sheet.
Melt white chocolate & butter together until smooth.
(Microwave in 20-second bursts, stirring each time.)
Whisk sugar, eggs, and yolks until pale and slightly thickened.
Stir in vanilla, then slowly whisk in melted white chocolate mixture.
Fold in flour and salt just until combined. Do not overmix.
Fill ramekins halfway, add 1 tsp raspberry preserves or 3 fresh raspberries in the center, then top with remaining batter.
Bake 11–13 minutes until edges are set but centers still soft.
Cool 1 minute, then carefully invert onto plates or serve directly in ramekins.