Ingredients

5 tablespoons unsalted butter, plus more for muffin tin

1 tablespoon all-purpose flour, plus more for dusting

14 ounces semisweet chocolate, chopped

2 tablespoons sugar

2 large eggs

1/4 teaspoon salt

Preparation

  1. Preheat oven to 375 degrees. Generously butter a standard 6-cup muffin tin. Dust with flour, tapping out excess; set aside.
  2. Put chocolate, butter, and 1 tablespoon sugar in a medium heatproof bowl set over a pan of simmering water; whisk occasionally until smooth. Remove from heat, and let stand until cool and thickened, 3 to 5 minutes. Process eggs and remaining tablespoon sugar in a food processor until pale and doubled in volume, about 2 minutes. Sift flour and salt into egg mixture; pulse to combine. Add chocolate mixture 1/4 cup at a time; pulse each addition until combined, about 10 times. (Batter will be thick.)
  3. Spoon mixture into the prepared muffin tin, filling cups three-quarters full; swirl tops with back of spoon. Bake until tops are springy to the touch, 18 to 20 minutes. Immediately turn out onto wire racks; reinvert, and let cool.