2-1/4 cups all purpose flour
1 tsp baking powder
3/4 tsp baking soda
1/4 tsp salt
3/4 cup unsalted butter, at room temperature
1-3/4 cups granulated sugar
2 large eggs
3 oz good quality dark chocolate, melted and cooled
1 tsp vanilla
1-1/4 cups milk
1.5 oz  good quality dark chocolate, chopped
1/2 cup chopped pecans

Preheat oven to 350.  Butter and flour a 13x9" pan.

Mix together flour, baking powder, baking soda and salt in a medium bowl.  Set aside. In a large mixing bowl, beat butter until light.  Add sugar and beat until light and fluffy. Add eggs one at a time, beating well after each addition.   Beat in melted chocolate and vanilla.  Add dry ingredients, alternating with milk, beating after each addition just until combined.  Stir in pecans and chopped chocolate.  Spread in prepared pan.  Bake 40 minutes or until toothpick inserted in center of cake comes out clean.  Cool in pan on wire rack.
 

Frosting

1/4 cup unsalted butter, at room temperature
2 cups confectioners' sugar
2 tbs milk
1.5 oz good quality dark chocolate, melted and cooled
1 tsp vanilla
1/2 cup coarsely chopped toasted pecans

Combine butter, sugar, milk, chocolate and vanilla in a bowl and stir
until smooth.

Frost cake and sprinkle with toasted pecans.