recipe is : chocolate brownies

i got this recipe from chef michael smith of the 'chef at home' show. i tweaked a wee bit here and there to suit my own preference
Ingredients

700g/25oz cooking chocolate
200g/0.75 cup butter
200g/2 cups flour
1 teaspoon baking powder
pinch of salt
4 tablespoons cocoa powder
5 small/med eggs
250g/1.25 cups sugar
2 tablespoons vanilla extract
Method

- preheat oven to 180C/350F.
- melt the chocolate and butter in a bowl over simmering water
- whisk together the flour, baking powder, salt and cocoa powder
- when the chocolate and butter have melted whisk them smooth
- add the eggs, sugar and vanilla to the chocolate and mix thoroughly
- add the flour mixture
- pour into a lightly greased and floured 9x13-inch pan
- bake for 45 minutes