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℉. 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 of the cheese, half of the bacon bits and salt. Mix well.
When potatoes are cool enough to handle, cut in half. Scoop out pulp and mash potatoes.
Then add to the cream cheese mixture. Beat with a mixer. Stir in milk, dry ranch dressing mix, and mix well.
Spread potato mixture in prepared pan. Bake uncovered 30 minutes. Remove from oven, sprinkle with remaining cheese, bacon pieces, and green onions.
Bake 5 minutes longer, or until cheese melts.
Notes
I have only made this in the oven, however, you could make this in the slow cooker. You will definitely want to spray the oven with non stick cooking spray, or use a slow cooker liner, but it would work.