Chocolate Espresso Torte

5 ounces semisweet chocolate, chopped
3 ounces unsweetened chocolate, chopped
8 tablespoons unsalted butter, cut up
4 eggs, room temperature
1/2 cup sugar
1/4 cup brewed double strength coffee -- room temperature
1 tablespoon sifted fine ground espresso beans
1/4 teaspoon salt
1/4 cup flour

Heat the oven to 350ºF (325ºF for dark pans). Butter an 8-inch cake pan and line the bottom with kitchen parchment. Butter the parchment and lightly flour the pan, shaking out the excess. In a small, heavy-based saucepan over medium heat, melt the chocolates and butter, stirring frequently. Set aside. Using the whisk attachment of a stand mixer, whip the eggs, sugar, brewed espresso, ground espresso beans, and salt on medium-high speed until thick and voluminous, at least 8 min.

Turn the mixer to low and mix in the butter-chocolate mixture. Turn off the mixer. Sift the flour over the batter and fold until all the ingredients are fully incorporated. Pour the batter into the prepared pan and bake until a skewer inserted in the center of the cake comes out clean, 25 to 30 min. Cool in the pan on a rack for 10 min. Set a plate over the torte and carefully invert the torte onto the plate; peel off the parchment. Flip the torte back onto the rack to cool completely before slicing.