Bake potatoes for 50 miutes at 425F. While potatoes are baking -- fry bacon slowly until crisp. Remove bacon and drain on paper towel and then crumble. Saute mushrooms and onions (until onions are clear) in bacon grease.
Cut 1/4 off top of baked potato lengthwise. Slice a thin layer off of the top and then spoon out the meat of the potato with a teaspoon into a mixing bowl.
Mix all ingredients together. Spoon mixture into potato shells (peelings). Bake at 425F for 15 minutes. During the last few minutes, more cheddar cheese can be added on top until melted.
Note: Potatoes may be prepared day before and baked for 30 minutes instead of 15 minutes at 375F. Also they may be frozen. When heating -- put frozen potatoes in oven for 45 minutes at 375F.