In medium skillet, cook bacon until crisp. Remove from pan, reserving drippings. Add onion to drippings and cook over medium high heat 2 minutes. Add cabbage and cook an additional 5 minutes or until wilted. Meanwhile, prepare mashed potatoes according to package directions. Season with salt and pepper. Put mashed potatoes in large bowl and fold in the onion/cabbage mixture and bacon. Put in serving bowl and place a large pat of butter on top. Serve.