- 1 cup heavy cream
- 7 oz fine-quality bittersweet chocolate (not unsweetened), finely chopped
- 1/2 cup Dutch-process unsweetened cocoa powder
- 1 1/4 cups all-purpose flour
- 1 cup sugar
- 1/2 teaspoon baking soda
- 1/8 teaspoon salt
- 2 whole large eggs
- 1 large egg yolk
- 3/4 cup well-shaken buttermilk
- 1/4 cup vegetable oil
- 1 teaspoon vanilla
- Unsalted butter for greasing griddle
- Bring cream to a boil in a 1-quart saucepan, then pour hot cream over chocolate in a bowl, gently whisking until smooth. Keep warm or at room temperature.
- Sift together cocoa, flour, sugar, baking soda, and salt into a large bowl, then whisk in eggs, yolk, buttermilk, oil, and vanilla until combined well.
- Heat a griddle or nonstick skillet over moderately low heat and lightly coat with butter.
- Working in batches of 2 or 3, pour 1/4 cup batter per cake onto hot griddle and cook until bubbles appear on surface, 1 to 2 minutes. Flip cakes with a large spatula and cook until tops spring back when pressed gently, about 1 minute more. Transfer to a plate and loosely cover with foil to keep warm. Add 1/2 teaspoon butter to griddle between batches.
- Serve cakes in stacks, topped with chocolate sauce.