Start off by peeling your potatoes using a knife or a potato peeler. Then give them a good rinse.
Then cut the potatoes into 1-2 inch cubes. Make sure the potato pieces are similar in size for even cooking.
Boil the potatoes with salt
Place the cut potatoes in a large stockpot and fill it with enough water to submerge all the potatoes. Roughly about 5 cups of water. Make sure the water is cold. That way the potatoes cook as the water heats up. 
 Now add 1 1/2 tablespoons of sea salt to the potatoes and bring the water to a boil. 
After the potatoes have boiled let them cook over medium-low heat for about 15 minutes. Or until the potatoes are fork-tender.
Strain the water out and add remaining ingredients
Carefully strain the water out of the pot while the lid is cracked open to keep the potatoes from falling out. 
Now add the softened butter, sour cream, heavy cream, and pressed garlic.
 Using an electric hand mixer, beat the mashed potatoes until smooth and creamy. Season as needed with salt. 
What to do with leftover mashed potatoesMade more creamy mashed potatoes than you needed? Don't worry, you can use them to make another delicious dish. Try these tasty mashed potato pancakes,turkey shepherd's pie, or make homemade gnocchi.