6 large eggs, separated
1 cup (226 grams) unsalted butter, cut into small pieces
9 ounces (255 grams) semisweet or bittersweet chocolate chopped
1 cup (200 grams) granulated white sugar, divided
1 teaspoon pure vanilla extract
1/4 teaspoon cream of tartar
Ganache: (Optional)
8 ounces (227 grams) semisweet or bittersweet chocolate, chopped
3/4 cup (180 ml) heavy whipping cream
2 tablespoons (28 grams) unsalted butter
1 tablespoon or brandy (optional)