Preheat your oven to 375°F (190°C). Grease the ramekins with butter and dust with sugar.
In a mixing bowl, mash the raspberries with half of the sugar.
In another bowl, whisk the egg whites with a pinch of salt until soft peaks form. Gradually add the remaining sugar and continue to whisk until stiff peaks form.
Gently fold the raspberry mixture into the egg whites until well combined.
Spoon the mixture into the prepared ramekins, filling them to the top. Run your thumb around the inside edge of each ramekin to help the soufflés rise evenly.
Bake in the preheated oven for 12-15 minutes, or until the soufflés have risen and are golden brown on top. Serve immediately.