Easy Chocolate Brownies

Bahan-bahan (9 porsi)

• 200 g / 14 tbsp unsalted butter ((1 3/4 US sticks))
• 200 g / 1 1/4 cups dark chocolate chips ((7 oz) (Note 1))
• 1 cup (175g) brown sugar (, loosely packed )
• 3 eggs (, lightly beaten)
• 1 tsp vanilla extract
• 1/2 cup (75g) plain flour
• 1/4 cup (30g) cocoa powder
• Pinch of salt
• 180 g /6oz dark chocolate block/bar (optional)
• 1.5 cups roughly chopped walnuts (or other nuts)