Preheat the oven to 180 C / Gas 4. Grease and line the bottom of a 20cm (8in) square tin with baking paper.
Break up the chocolate, and put 175 grams (6oz) in a bowl and set over a pan of simmering water until melted and smooth. Cool slightly.
Whisk the butter and sugar together until fluffy in a medium bowl. Whisk in the eggs and vanilla extract, then stir in the melted chocolate.
Sift the flour and salt over the mixture and fold in. Then gently fold in the saved broken chocolate and then raspberries. Spoon the mixture into the tin, spread into the corners and level with a plastic spatula.
Bake for 30 to 35 minutes. Cool before cutting into squares.
Brownies should be firm on the outside, but gooey and fudge-like on the inside!