Make the Raspberry Sauce

Place the raspberries and 4 tablespoons of sugar in a blender and puree.

Strain the puree through a fine sieve over a bowl, pushing down on the berries to extract the fruit and juice. Discard the seeds and taste for sweetness. Cover and place in the fridge until needed.

Make the Souffles

Preheat the oven to 375°F (190°C).

Thoroughly butter the bottom and sides of around four 6oz (180ml) ramekins with butter, and then coat with granulated sugar. Place on a baking sheet and set aside.

Melt the white chocolate over a double boiler, and set aside to cool. Try not to stir it, just let it melt.

While the chocolate is cooling, in a small bowl whisk together the sugar, flour and salt. Set aside.

Place the egg whites and cream of tartar in a stand mixer or large bowl, and whip on high speed until it can hold soft peaks.

Lower the speed, and continue whipping the egg whites while you add the flour mixture, one spoon at a time, until glossy, and it has stiffened. Remove from the mixer.

Whisk the egg yolks and vanilla extract into the cooled white chocolate until smooth.

With a metal spoon, gently fold in ⅓ of the egg whites mixture into the chocolate mixture until mostly combined, then fold in the remaining egg whites until evenly mixed.

Fill the souffle batter flush with the top of the ramekins, using a knife or offset spatula to smooth the top.

Using your thumb and index finger, pinch the edge of one of the ramekins and run your pinched fingers around the rim of the ramekin to separate the batter from the top edge of the ramekin. Repeat with the other ramekins. (Doing this will help the souffle rise.)

Return the ramekins to the baking sheet and bake for roughly 13-14 minutes, until the souffles have risen and the tops are a light golden brown.

Carefully remove from the oven, dust with powdered sugar and serve immediately with the raspberry sauce poured over top.