1. Preheat the oven to 180°C (160°C for fan ovens) Gas Mark 4.
2. Melt the butter with a quarter of the chocolate gently in the microwave.
3. Beat the eggs with the sugar in a large bowl until light and fluffy and then sift in the flour and baking powder. Stir in the melted chocolate mixture.
4. Add the rest of the chocolate. Spoon into the tin. Beat the caramel in a small bowl and swirl into the mix.
5. Bake for about 30 minutes, they should still be sticky in the middle if you test with a knife. When cool cut into squares.
Recipe courtesy of Carnation®