Heat oven to 375 degrees F. and lightly butter a 9" x 13" casserole dish.
Peel half of the potatoes and leave the other half with skins on (if you prefer, you could remove all the skins). Cube the potatoes into small pieces and place in a large pot of lightly salted water. Bring the pot to a boil and cook until potatoes are fork tender. Drain and return potatoes to the pot.
Meanwhile melt 8 tbsp of butter in a large skillet and add the garlic and green onions to the skillet, sautéing until the garlic is fragrant, about 1 minute.
Add the cream, milk, and melted butter mixture to the pot of potatoes. Use a potato masher to mash the potatoes until smooth and creamy. Stir in the cheese, bacon crumbles, salt and pepper.
Transfer the potato mixture to the prepared casserole dish.
To prepare the topping, lightly crush the pasta chips and toss with 2 tbsp of melted butter, until evenly coated. Sprinkle the pasta chips over the mashed potatoes in an even layer and then transfer to the oven. Bake for 15 to 20 minutes, or until the pasta chips are a golden brown.
Feel free to substitute the mozzarella with equal amounts cheddar. Just taste the potatoes before adding additional salt, as cheddar cheese tends to be a little more salty than mozzarella.