1. Heat oven to 350°F. Butter bottom and sides of two 9-inch round baking pans. Line bottoms with wax paper; butter paper.
2. Melt butter in small saucepan; remove from heat. Add cocoa, stirring until blended; cool slightly. Beat eggs in large bowl until foamy; add salt and vanilla. Gradually add sugar, beating well. Add cooled chocolate mixture; blend thoroughly. Fold in flour. Stir in pecans. Pour mixture into prepared pans.
3. Bake 20 to 25 minutes or until wooden pick inserted in center comes out clean. Do not overbake. Cool 5 minutes; remove from pans to wire racks. Carefully peel off paper. Cool completely. Spread CREAMY COFFEE FILLING between layers, over top and sides of cake. Garnish with chocolate curls, if desired. Refrigerate 1 hour or longer before serving. Cover leftover cake; store in refrigerator. 10 to 12 servings.
CREAMY COFFEE FILLING
1-1/2 cups cold whipping cream
1/3 cup packed light brown sugar
2 teaspoons powdered instant coffee
Combine all ingredients; stir until instant coffee is almost dissolved. Beat until stiff. About 3 cups filling.
MAKE AHEAD DIRECTIONS: Cooled cake may be wrapped and frozen up to 4 weeks; thaw, wrapped, before filling and frosting.