4 tablespoons unsalted butter, room temperature, plus more for muffin tins
1/3 cup granulated sugar, plus more for muffin tins
3 large eggs
1/3 cup all-purpose flour
1/4 teaspoon salt
8 ounces bittersweet chocolate, melted
confectioners' sugar, for dusting
vanilla ice cream, for serving
Preheat oven to 400 degrees. Generously butter 4 cups of a standard muffin tin. Dust with granulated sugar, and tap out excess. Set aside.
In the bowl of an electric mixer, cream the butter and granulated sugar until fluffy. Add the eggs one at a time, beating well after each addition. With the mixer on low speed, beat in the flour and salt until just combined. Beat in the chocolate (do not overmix). Divide the batter evenly among the prepared cups.
Place muffin tin on a baking sheet; bake just until the tops of the cakes no longer jiggle when the pan is slightly shaken, 8 to 10 minutes.
To serve, turn out the cakes, and place on serving plates, top sides up. Dust with confectioners' sugar and serve with vanilla ice cream, if desired.