Pre-heat the oven to 190 ºC and line an 8 x 8 inch baking pan with greaseproof/baking paper.
In a bowl above simmering water, melt together white chocolate and butter. After they are melted, allow to cool until warm to touch.
Add the caster sugar, eggs + egg yolk, vanilla extract, salt and milk, and mix well until evenly combined.
Sift together gluten free flour and xanthan gum, and add them to the batter. Mix well until no flour clumps remain.
Transfer the white chocolate brownie batter into the baking pan and "sprinkle" the top with raspberries.
Bake in the pre-heated oven at 190 ºC for about 25 minutes or until an inserted toothpick still comes out a bit dirty, but the top is a light golden brown colour.
Allow to cool, cut into pieces and enjoy!
The white chocolate brownies keep well in a closed container in a cool dry place for about 3 - 4 days (but only if very well hidden).