In a double boiler or microwave, melt chocolate and butter; cool for 20 minutes. In a mixing bowl, beat eggs and sugar until thick and lemon-colored, about 4 minutes. Gradually beat in melted chocolate and vanilla. Combine flour, baking powder and salt; add to chocolate mixture. Stir in chips and pecans. Pour into a greased 15x10x1-inch baking pan. Bake at 350° for 40-45 minutes or until golden brown. Cool on a wire rack.