1/2 pound unsalted butter
3 ounces unsweetened chocolate
2 ounces semisweet chocolate
2 cups sugar, divided
4 eggs
1 1/4 cups all-purpose flour
3 tablespoons unsweetened cocoa
1/4 teaspoon salt
1/2 teaspoon vanilla extract
Preheat the oven to 350 degrees.

In the top of a double boiler, melt the butter and both chocolates over simmering water. Gradually whisk in 2/3 cup sugar. Remove from the heat.

In a large mixing bowl, whisk the eggs and the remaining 1 1/3 cups sugar. Set the bowl over a pot of simmering water and whisk until the mixture warms and the sugar dissolves; test by rubbing a small amount of the mixture between your fingers -- it should feel smooth. Then beat the mixture with an electric mixer until thickened and pale yellow and increased in volume, about 5 minutes. Add the melted chocolate-butter mixture and beat until smooth and shiny. Add the flour, cocoa, salt, and vanilla and beat well.

Pour the batter into a greased 13-by-9-by-2-inch pan and bake for 30 minutes or until a tester comes out clean. Cool on a wire rack. Cut in squares.

Makes 24 brownies.