Preheat the oven to 350F.
Lightly butter a 9-inch springform pan and set aside.
In a medium saucepan, melt the chocolate and butter over the lowest heat, do not rush this process, melting the choclate too quickly will cause it to"shock" into a hard lump. Mix in the cocoa powder and espresso powders until smooth and set aside for a few minutes to cool.
While the chocolate is cooling, whisk together the eggs, sugar, and flour until they are completely combined and foamy. Fold the egg mixture into the chocolate until the color is uniform and pour the batter into the prepared pan. Place into the center of the preheated oven and bake for 45 minutes or until a toothpick pulls out moist crumbs when inserted near the center of the torte. If the pick is sticky, then cook for a little longer.
Allow the cake to cool in the pan on a rack for 15 minutes. Run a knife or inverted spatula along the edges of the gateau and loosen the sides of the pan. Cool for 5 minutes and remove the sides of the pan. Invert the cake onto a pretty cake platter and cool completely before serving decorated as you wish.