INGREDIENTS

FOR THE CAKE

• 1/2 cup unsalted butter, cut into small pieces, plus more for pan
• 1 cup all-purpose flour, (spooned and leveled), plus more for pan
• 1/2 tsp salt
• 1/4 tsp baking powder
• 8 oz semisweet chocolate, coarsely chopped1
• 1/4 cups sugar1 tsp pure vanilla extract
• 2 large eggs
• 1/2 cup low-fat buttermilk
• 3/4 cup shelled, unsalted pistachios, coarsely chopped

FOR THE CHOCOLATE GANACHE AND TOPPING

• 1/2 cup heavy cream
• 4 oz semisweet chocolate, coarsely chopped
• 1/4 cup shelled unsalted pistachios, coarsely chopped

Instructions

Make cake:

1. Preheat oven to 350 degrees.
2. Butter and flour an 8-inch round cake pan; line bottom with parchment or waxed paper.
3. In a medium bowl, whisk together flour, salt, and baking powder. Set aside.
4. In a large heatproof bowl set over (not in) a saucepan of simmering water, melt butter and chocolate, stirring frequently, 4 to 5 minutes. Remove bowl from pan.
5. Whisk in sugar and vanilla, then eggs, buttermilk, and pistachios.
6. Fold in flour mixture just until combined.
7. Pour batter into prepared pan. Bake until a toothpick inserted in center comes out with a few moist crumbs attached, 60 to 70 minutes.
8. Let cool in pan 5 minutes; run a knife around edge, and invert onto a wire rack. Remove paper, and let cool completely, about 3 hours. (To store, wrap in plastic, and keep at room temperature, up to 3 days).

Make ganache:

1. In a small saucepan, bring cream to a simmer; remove from heat.
2. Add chocolate, and let stand 5 minutes; whisk until smooth.
3. Let cool until mixture falls back in ribbons when lifted with a spoon, 2 to 6 minutes.
4. Set cake on a serving platter; tuck strips of parchment paper under edge of cake to prevent ganache from dripping on platter. Pour ganache onto center of cake; using a table knife, spread evenly over the top and down the sides. Let set, about 30 minutes. Remove paper from under cake; sprinkle top with pistachios.