Peel and dice the russet potatoes into equal-sized chunks.
Place the potatoes in a large pot and cover with water.
Add a pinch of salt to the water and bring to a boil over medium-high heat.
Reduce heat and simmer until the potatoes are fork-tender, about 15-20 minutes.
Drain the potatoes and return them to the pot.
Add the butter and milk to the potatoes and begin mashing.
Stir in the sour cream, mixing until creamy and smooth.
Season with salt, pepper, and garlic powder if desired.
Fold in half of the cheddar cheese and half of the crumbled bacon.
Transfer the mashed potatoes to a serving bowl and top with remaining cheese, bacon, and chives.