Preheat the oven to 350 degrees. Lightly grease an 8" square baking pan.

Melt the chocolate and butter together in the top part of a double boiler set over barely simmering water.

When the ingredients have melted, blend them thoroughly and remove the pan from the heat.

Combine the eggs and sugar in a large bowl and beat them 2-3 minutes or until the mixture is thick and pale.

Mix the flour, baking powder and salt in a bowl and stir this mixture into the chocolate mixture. Stir in the vanilla extract and nuts, if used.

Spoon the batter into the prepared pan. Bake for 30 minutes. Cool the brownies in the pan. Cut them into 16 squares.