Preheat your oven to 400°F.
Fill a large pot with water and bring it to a boil over high heat.
Add the potatoes, reduce the heat to medium, and cook until they are fork tender, about 20 to 25 minutes. Keep an eye on them because you want them soft but not falling apart.
Drain the potatoes and return them to the warm pot.
Mash the potatoes into rough chunks, then add the Greek yogurt, milk, butter, half of the cheese, garlic powder, salt, and pepper. Mash again until the mixture is creamy and the ingredients are fully combined.
Transfer the potatoes to a greased 8x8 baking dish and use a spatula to spread them into an even layer.
Sprinkle the remaining shredded cheddar and cooked bacon over the top.
Bake for 20 to 25 minutes, or until the cheese is melted and lightly bubbling around the edges.
Remove from the oven, garnish with chopped chives or green onions, and serve warm.