Peel the russet potatoes and cut them into uniform 1-inch chunks.

Fill a large pot with cold water and add potatoes, then bring to a boil.

Once boiling, add 2 tablespoons of salt to the water and reduce heat to a rolling boil. Boil the potatoes for 15 to 18 minutes, until a fork pierces them easily.

While potatoes cook, fry 8 slices of bacon in a skillet over medium heat until crispy, about 8 to 10 minutes. Chop the bacon into bite-sized pieces once cool enough to handle.

Heat the whole milk in the microwave or a small saucepan until steaming, about 1 to 2 minutes.

Pour potatoes into a colander and let them sit for 30 seconds to allow excess water to drain.

Transfer hot potatoes to a large bowl and immediately add the softened butter and 1 teaspoon salt. Begin mashing with a hand-held potato masher, using firm pressure in a downward and twisting motion.

Gradually add the warm milk while continuing to mash, stirring between additions until the potatoes reach your desired consistency. Fold in the sour cream and shredded cheddar cheese using a wooden spoon, stirring gently until fully combined.

Season with black pepper and taste, adjusting salt as needed.

Gently fold in the crumbled bacon, fresh chives, and green onions using a wooden spoon. Reserve a handful of bacon and chives to sprinkle on top just before serving.

Transfer to a serving bowl and top with reserved bacon, chives, and crispy fried onions if using. Serve immediately.