Wash and pierce potatoes in several places with a fork.
Microwave on high 10 minutes until tender.
Set aside to cool slightly.
Preheat oven to 350 degrees F.
Grease an 11 X 7-inch baking pan.
Combine cream cheese and sour cream in a large bowl; beat until smooth.
Add yellow onion, half the cheddar, half the bacon bits, and salt.
When potatoes are cool enough to handle, cut in half.
Scoop out pulp and add to cream cheese mixture, using a fork to mix well.
Stir in milk.
Add dry ranch dressing.
Spread potatoe mixture in prepared pan.
Bake uncovered, 30 minutes.
Remove from oven, sprinkle with remaining cheddar, remaining bacon bits, and green onions.
Bake 5 minutes longer, or until cheese melts.