Preheat oven to 350F/180C. Line the base and sides of an 8×8-inch baking pan with foil, leaving enough overhang on the sides for lifting the brownies out after baking.

In a medium heat-proof bowl, place white chocolate and butter. Place bowl over a saucepan of simmering water and stir occasionally until chocolate and butter have melted. Transfer mixture to a large bowl, then add sugar and mix to combine. Add eggs, one at the time, mixing until combined. Stir in vanilla. Sift flour and salt, then fold into batter just until combined. Fold in raspberries.

Pour batter into prepared pan and smooth the top. Bake for 17-20 minutes, until top is golden and a toothpick inserted into the center comes out with a few moist crumbs. Avoid overbaking, which will make the brownies dry. Let brownies cool completely on a wire rack, then lift them out of the pan and cut into squares (or refrigerate until completely set for perfect cutting).

Brownies can be kept at room temperature or in the refrigerator in an airtight container for up to 3 days. Alternatively, they can be frozen for up to 2 months, then thawed overnight in the fridge.