Triple Chocolate Brownies

This recipe comes from Nigella Lawson and I'm posting it by request. I have not made it yet, but hope to do so in the future.

• Ready In: 55 mins
• Yields: 18 Brownies

Ingredients

• 1 1⁄2 cups butter (3 Sticks)
• 2  tablespoons butter
• 12  ounces bittersweet chocolate (Good Quality)
• 6  eggs
• 1 3⁄4 cups  superfine sugar
• 1  tablespoon vanilla extract
• 1 1⁄2 cups flour
• 2  tablespoons flour
• 1  teaspoon salt
• 1⁄2 cup white chocolate chips
• 1⁄2 cup  semi-sweet chocolate chips
• 2  teaspoons powdered sugar, for garnish

Directions

1. Preheat oven to 350 degrees.
2. Generously grease a 9 x 11 1/4 baking dish and line with parchment paper.
3. Melt the butter and bittersweet chocolate in a large heavy saucepan over low heat.
4. Remove from heat and let cool slightly.
5. In a large bowl beat the eggs with the sugar and vanilla extract.
6. Add the slightly cooled chocolate mixture to the eggs and sugar and beat well.
7. Fold in the flour and salt.
8. Stir in the white chocolate chips and the semisweet chocolate chips.
9. Pour batter into prepared pan.
10. Bake for about 25 minutes or until the top dries to a slightly paler brown speckle with the middle remains dark, dense and gooey.
11. Do not overbake.
12. The difference between gooey brownies and dry ones is only a few minutes.
13. Sprinkle with powdered sugar.