- 8 ounces bittersweet chocolate (70 percent)
- 6 tablespoons unsalted butter
- 2 large eggs
- 1 cup sugar
- 1 teaspoon pure vanilla extract
- 1/4 teaspoon salt
- 1/4 cup all-purpose flour
- 8 tablespoons (1 stick) unsalted butter , melted
- 1/4 cup sugar
- 1/4 teaspoon vanilla extract
- 1/4 teaspoon salt
- 1 cup all-purpose flour
- 2/3 cup shelled walnuts , coarsely chopped
- 1 cup chilled creme fraiche , for topping
- Whole nutmeg
To make brownie: Place chocolate and butter in top of a double boiler over almost-simmering water. Stir frequently until chocolate is melted and mixture is smooth and very warm to touch.
Remove from heat and set aside. In a medium bowl, beat eggs, sugar, vanilla and salt at high speed with an electric mixer, until mixture is thick and light in color, 3 to 4 minutes. Stir in flour. Scrape in warm chocolate mixture and fold with a rubber spatula until just combined. Set aside until needed.
To make crust: In a medium bowl, combine melted butter, sugar, vanilla and salt. Stir in flour, then walnut pieces. Turn out into pan; press dough evenly across bottom. Bake until crust is fully golden brown, 15 to 20 minutes.
Remove pan from oven, but leave oven on. Scrape brownie batter onto hot crust and spread evenly, swirling surface. Return to oven and bake just until a toothpick inserted in two or three places comes out clean, 20 to 22 minutes. Set pan on a rack to cool. (If serving brownies warm, cool just long enough to remove from pan without cracking.) To remove brownies from pan, lift edges of foil. Transfer to a cutting board. Gently slide a thin spatula between crust and foil; slide brownies off foil.
To serve, cut with a heavy knife. Whip crème fraîche just until it holds shape. Divide brownies among serving plates and grate nutmeg over brownies (use a Microplane or nutmeg grater to get the topping just right). Top with a dollop of crème fraîche and a little more grated nutmeg.
Note: Crème fraîche is similar to sour cream but lighter and milder. If you can't find it in your local market, substitute sour cream, unsweetened whipped cream, or a mixture of both.