Step 1

Preheat the oven to 400 degrees F. Grease a 2-quart baking dish with cooking spray.

Step 2

Peel the potatoes and cut them into 1-inch cubes. Place the potatoes and salt in a pressure cooker with water to cover and bring to a boil. Reduce the heat and simmer the potatoes until very tender, about 5 minutes. (If you do not have a pressure cooker, boil the potatoes in a pot of water with a pinch of salt until tender, about 20 minutes.)

Step 3

While the potatoes boil, cook the bacon in a medium skillet over medium heat until browned and cooked through, 8 to 10 minutes. Drain the bacon on paper towels and, when cool enough to handle, crumble it into small pieces. Set aside.

Step 4

Add the milk, mayonnaise, sour cream, butter, garlic salt, pepper and 1 cup of the cheese to a stand mixer with a paddle attachment. Whip the mixture until thoroughly combined. Drain the potatoes and add to the mixer. Mix again to combine and the potatoes are whipped smooth.

Step 5

Spoon the mixture into the prepared baking dish. Sprinkle the crumbled bacon and remaining 1 cup cheese over the top and bake until the cheese is melted and the casserole is heated through, about 20 minutes.