In a large skillet cook the 6 slices bacon over medium heat until crisp. Remove bacon and drain on paper towels, reserving 1 tablespoon drippings in skillet. Crumble bacon; set aside.
In a large saucepan combine potatoes, the water, and bouillon granules. Bring to boiling; reduce heat. Simmer, covered, about 15 minutes or until potatoes are very tender.
Meanwhile, add onions to the reserved bacon drippings. Cook over medium-low heat for 8 to 10 minutes or until tender and golden, stirring occasionally. Remove from heat. If desired, set aside some of the sauteed onions for garnish.
Mash potatoes slightly with a potato masher. Stir in milk, 1/4 teaspoon pepper, the reserved bacon from Step 1, and the onions; heat through. If desired, season to taste with additional pepper and garnish with extra crisp-cooked bacon and reserved sauteed onions.