Add your butter to a pan, melting on a medium heat, then reduce the heat slightly and allow the butter to brown for between 5-10 minutes. Keep a close eye on this so it doesn’t burn, then once browned to your liking, remove from the heat and set aside.
Preheat your oven to 180°C.
Pour your brown butter into a mixing bowl, adding your brown sugar, then mix until fully combined.
Add your eggs to the bowl, whisking until fully incorporated, then add your vanilla and dry ingredients, mixing until the flour is completely folded through.
Add your raspberries and chunks of white chocolate, folding through, then pour your cake batter into a lined square tin, spreading your batter around and bake for 25 minutes, until risen, crisped up and golden brown.