Preheat oven to 325 degrees F (165 degrees C). Grease and flour a 10 inch tube pan. Mix together the flour and baking powder; set aside.
In a large bowl, cream together the butter, brown sugar and white sugar until light and fluffy. Beat in the eggs one at a time, then stir in the vanilla. Beat in the flour mixture alternately with the milk, mixing just until incorporated. Sir in the chopped pecans. Pour batter into prepared pan.
Bake in the preheated oven for 60 to 75 minutes, or until a toothpick inserted into the center of the cake comes out clean. Let cool in pan for 10 minutes, then turn out onto a wire rack and cool completely.