Peel and cube the potatoes, then place them in a large pot.
Fill the pot with water, ensuring the potatoes are submerged.
Bring the water to a boil over medium-high heat.
Cook the potatoes until tender, about 15-20 minutes.
Drain the potatoes and return them to the pot.
Add butter, milk, salt, and pepper to the potatoes.
Mash the potatoes until smooth and creamy.
Stir in half of the cheese, bacon bits, and sour cream.
Transfer the mashed potatoes to a serving dish.
Top with remaining cheese, green onions, and additional bacon bits before serving.