Line the bottom of a greased 9-in. springform pan with waxed paper; grease the paper and set aside.
In a microwave, melt butter and chocolate; stir until smooth. Cool. In a large bowl, beat eggs until frothy; gradually add sugar, beating for 4-5 minutes or until mixture triples in volume. Gradually beat in chocolate mixture and vanilla. Combine pecans and flour; fold into batter. Pour into prepared pan.
Bake at 350° for 30-35 minutes or until cake springs back when lightly touched. Cool on a wire rack for 15 minutes. Run a knife around edge of pan; remove sides of pan. Invert cake onto wire rack; carefully remove pan bottom and waxed paper. Cool completely.
Place chocolate chips in a small bowl. In a small saucepan, bring cream just to a boil. Pour over chocolate; whisk until smooth. Stir in butter.
Transfer to a small bowl; cover and refrigerate until mixture reaches spreading consistency, stirring occasionally. Place cake on a serving plate. Pour ganache over cake and quickly spread to edges.
In a microwave, melt white chocolate; stir until smooth. Transfer to a heavy-duty resealable plastic bag; cut a small hole in a corner of bag.
Pipe thin horizontal lines 1 in. apart over ganache. Use a sharp knife to draw right angles across the piped lines. Press pecans onto side of torte. Top with pecan halves if desired. Cover and refrigerate for 30 minutes or until set. Yield: 18 servings.
Recipe by World Wide Chocolate Magazine | Recipes, Reviews, Videos, News, Articles at http://worldwidechocolate.com/magazine/chocolate-truffle-torte/