3 cups all-purpose flour, plus more for preparing pan
1 1/4 teaspoon baking soda
1/4 teaspoon kosher salt
2 cups espresso or very strong coffee, cooled
Bring 1 inch water to a simmer in the bottom of a double boiler or saucepan.
Place the chocolate and 1 1/2 cups butter in the top of the double boiler or in a heatproof bowl placed over the pan. Heat, stirring frequently, until melted and smooth.
Add the dry ingredients and mix just until all the flour disappears. Pour and scrape the batter into the prepared pan; it will come almost to the top.
Remove from the oven and let the cake rest in the pan on a wire rack for 10 minutes before inverting onto a cake plate. Let cool to room temperature before serving. Or you can decorate the cake with chocolate butter cream frosting like I did.
CHOCOLATE BUTTERCREAM FROSTING
1/2 cup shortening
1/2 cup butter
3/4 cup sifted cocoa
3-4 tbsp. milk