Preheat oven to 350 degrees F. Generously spread margarine over the bottom and 1-1/2 inches up the sides of a 9-inch springform pan. Reserve 1 or 2 tablespoons of the ground nuts. Set aside. Sprinkle remaining nuts evenly in pan.
In a medium mixing bowl beat the egg yolks with an electric mixer on high speed for 5 minutes or until thick and lemon-colored.
Gradually beat in 1/4 cup of the granulated sugar until eggs are slightly thickened. At low speed, beat in the melted chocolate. Dissolve instant espresso or coffee crystals in the 2 tablespoons of hot water. Stir into chocolate mixture.
In a large mixing bowl, beat egg whites until soft peaks form. Gradually add the remaining 1/4 cup granulated sugar; beat until stiff peaks form. Gently fold egg whites into yolk mixture. Spread evenly in springform pan.
Bake 20 to 25 minutes or until set. Cool on wire rack 15 minutes. (Center will dip on cooling and crust edges will be crumbly.)
Using a thin metal spatula, loosen torte from the sides of the pan. Remove sides of the pan; cool torte completely. Serve immediately or cover and chill for up to 24 hours. If chilled, allow torte to stand at room temperature for 15 minutes before serving.
To serve, cut torte into wedges and place on dessert plates. Sift powdered sugar and sprinkle reserved ground nuts over each serving. Garnish with chocolate curls. Makes 10 servings.