How to Make It
Put the capers in a small bowl and cover with 2 inches of water. Let soak for 1 hour. Drain and coarsely chop the capers.
Meanwhile, in a small saucepan, boil the brewed espresso over high heat until reduced to 2 tablespoons, about 5 minutes.
In a medium saucepan, bring the stock to a simmer; cover and keep warm over low heat. In a large saucepan, heat the olive oil. Add the onion and cook over moderately high heat, stirring occasionally, until softened, about 3 minutes. Add the rice and cook, stirring, until just translucent, about 2 minutes. Add the wine and simmer for 2 minutes. Add the espresso beans and 1 cup of the hot stock and cook over moderate heat, stirring constantly, until absorbed. Repeat the process using a total of 5 cups stock and stirring until the rice is al dente and bound in a creamy sauce, about 20 minutes total.
Remove the risotto from the heat and discard the espresso beans. Stir in the butter and cheese; then stir in the remaining 1/4 cup of stock. Season the risotto with salt and pepper and spoon onto plates. Scatter the chopped capers over the risotto and the reduced espresso around it. Garnish with the espresso powder and serve right away.