1/4 cup soft unsalted butter, plus more for greasing
12 ounces bittersweet chocolate
1/2 cup granulated sugar
4 large eggs, beaten with a pinch of salt
1 teaspoon vanilla extract
1/3 cup all-purpose flour
6 individual (6 ounce) custard cups, buttered
Baking parchment

Preheat oven to 400 degrees F, putting a baking sheet in at the same time.

Lay 3 of the custard cups on a sheet of doubled baking parchment. Draw around them, remove, and then cut out the discs as marked. Press into base of the cups.

Melt the chocolate and let it cool slightly.

Cream together the butter and sugar, and gradually beat in the eggs and salt and vanilla extract. Add the flour, and when smoothly combined scrape in the cooled chocolate, blending into a smooth batter. Divide batter between the 6 custard cups. Quickly remove the baking sheet from the oven, arrange the cups on it and replace into the oven. Bake for 10 to 12 minutes, and as soon as you take them out of the oven, tip onto small plates or shallow bowls.

Serves 6.