Melt the butter and mix the wet ingredients

• Melt the butter and let it cool slightly.
• Whisk in the sugar, eggs and vanilla extract until smooth.

Add the dry ingredients

• Sift in the cocoa powder, salt, baking powder and flour.
• Fold until just combined, then stir in the chocolate chips.

Bake the brownies

• Pour the batter into the baking dish and top with the chocolate bar pieces.
• Bake at 180 °C until the top is set and a toothpick comes out with moist crumbs.

Cool and cut

• Let the brownies cool completely in the dish.
• Cut into squares and serve.