Place your potato cubes and minced garlic into a tall cooking pot. Fill with water until the potatoes are covered. Add 1 tablespoon of salt to the water and bring the water to boil. Once boiling, lower the heat and simmer for 15-20 min.
Let potatoes cook until you can cut the potatoes easily with a butter knife.
Drain the potatoes and immediately mash them. Use a potato masher or a electric mixer, mash until they are completely smooth.
Place the butter, heavy cream and milk into a microwave safe bowl and heat until the butter melts into the milk and heavy cream. Add the butter mixture to your potatoes and mix to incorporate.