1. Preheat oven to 180 Degrees Celsius.

2. Butter a 9-inch square baking pan. Line bottom and sides with parchment or baking paper. Butter the paper.

3. Melt butter and chocolate in a double boiler or heatproof bowl set over a saucepan of simmering water, stirring occasionally, until smooth.

4. Remove from heat. Mix flour, baking powder and salt together in a medium bowl. Whisk eggs, sugar and vanilla together in a large bowl until the mixture lightens in colour. Add chocolate to the eggs and stir to combine well. Add flour to the chocolate butter, stirring with a wooden spoon, until combined.

5. Pour batter into prepared pan, Bake 30 minutes, or until top is set and sides being to pull away from pan. Brownies will be fudgy and a wooden pick will not come out clean.