1. Heat oven 350°. Line 15x10x1 inch pan with foil; spray 13x9 inch (3 quart) glass baking dish with cooking spray. Pierce sweet potatoes several time with fork. Place in pan. Bake about 1 hour 15 minutes or until tender. Cool 10 minutes. When potatoes are cool enough to handle, peel potatoes and cut out any eyes or dark spots.
2. Meanwhile, cook bacon as desired until crisp; chop. In small bowl, mix bread crumbs and 1 tablespoon butter; set aside.
3. In large bowl, mash potatoes with potato masher. Stir in chopped bacon, sour cream, 1/4 cup butter, the onions, salt and pepper until well blended. Spread mixture in baking dish, or form individual servings in dish with 1/2-cup ice cream scoop or measuring cup. Sprinkle crumb mixture evenly over top.
4. Bake 20-30 minutes or until thoroughly heated and bread crumbs just begin to brown.
HIGH ALTITUDE (3500-6500 ft) In step 1 bake potatoes 1 hour 15 minutes to 1 hour 30 minutes. In step 4, bake casserole 30-40 minutes.
This casserole can be made the day before, just cover and refrigerate until ready to bake.