In a microwave, melt chocolate with the water; stir until smooth. Cool slightly. In a large bowl, cream butter and brown sugar until light and fluffy. Add 1 egg at a time, beating well after each addition. Beat in vanilla, then chocolate mixture., Combine the flour, latte mix, baking soda and salt; add to creamed mixture alternately with sour cream., Transfer to 3 greased 5-3/4x3x2-in. loaf pans. Bake at 350° for 35-40 minutes or until a toothpick inserted in the center comes out clean. Cool for 10 minutes before removing from pans to a wire rack to cool completely., For frosting, combine the confectioners' sugar, butter, latte mix, vanilla and enough milk to achieve desired consistency. Frost tops of loaves.