Peel the potatoes and cut them into evenly sized chunks (about 1-2 inches). This helps them cook evenly.
Place the potatoes in a large pot and cover them with cold water. Add a pinch of salt to the water.
Bring the pot to a boil over medium-high heat, then reduce to a simmer and cook the potatoes for about 15-20 minutes, or until they are fork-tender.
Once the potatoes are cooked, drain them in a colander and return them to the pot.
Add the butter, milk, cheddar cheese, garlic powder, salt, and pepper to the potatoes.
Using a potato masher or an electric mixer, mash the potatoes until they reach your desired consistency (smooth or slightly chunky).
Taste and adjust seasoning if necessary. If they’re too thick, you can add a little more milk to achieve your preferred creaminess.
Serve the cheesy mashed potatoes hot, garnished with chopped chives if desired.