Boil the potatoes: Boil the potatoes and peeled garlic cloves in salted water until fork tender. You should be able to very easily mash the potato piece with a fork.
Dry and mash: Once the potatoes are boiled, drain them and return them to the pot over medium heat. Once the potatoes are dry, mash the potatoes to get rid of the majority of lumps.
Add in the mix-ins: Add in the heated cream mixture in two increments. Fold in with a wooden spoon or a rubber spatula, and add the remaining cream. Mix in the sour cream and half the cheddar cheese and combine.
Top and bake: Transfer the mashed potato mixture to a baking dish, and top with the remaining cheese and bacon. Bake for 15 minutes, and broil on LO for another 2-3 minutes. Finish with green onions out of the oven.