1/2 cup all purpose flour
Combine flour, baking powder and salt in small bowl; whisk to blend. Stir chocolate and butter in top of double boiler set over simmering water until melted and smooth. Remove from over water. Cool mixture to lukewarm.
Preheat oven to 350°F. Line 2 large baking sheets with parchment or waxed paper. Drop batter by spoonfuls onto sheets, spacing two inches apart. Sprinkle with a pinch of flaky sea salt, if you’re using it. Bake just until tops are dry and cracked but cookies are still soft to touch, about 12 to 15 minutes. Cool on sheets. (Can be made 2 days ahead. Store airtight at room temperature.)
I know that it will be impossible to let them cool completely, but they really taste a lot better cool, as they continue baking once they come out of the oven.