Peel, wash and cut on cubes potatoes and place them in a large stock pot with cold water. The water must cover the potatoes. Add one teaspoon of salt and cover with the lid.
Place the saucepan on the stove and turn the heat on high. Bring the water with the potatoes to boil. Reduce the heat to low or simmer and cook for 20 minutes.
To make sure potatoes are cooked, take one potato out of the stock pot. Place it on a plate or cutting board and cut the potato in half with a small pairing knife. Taste it, if it's done to your liking. The potato has to be soft and easy to cut.
Drain cooked potatoes and keep them in the stock pot. Add 3 tbsp of butter onto steaming potatoes and start mashing the potatoes with hand electric mixer. Then start mixing the potatoes on lowest speed.
The potatoes will have crumble texture. Continue mixing with hand mixer and slowly add reheated milk. Potatoes will slowly come together and create creamy and fluffy texture. Don't over mix, or the potatoes will become sticky and gluey. If you feel the potatoes are very thick add more warm milk. Salt them to taste, if necessary.
Use a wooden spoon or spatula to transfer the mashed potatoes to a larger bowl. Decorate with chopped parsley and drizzle with 1 tbsp of melted butter.
Serve the mashed potatoes immediately, when hot!