Prepare a large, heavy pot of water, about 2/3 full, adding about 1/2 Tablespoon of salt to the water. Bring the water to a boil over high heat. Add the potatoes very carefully to avoid splashing hot water out of the pot. Boil the potatoes until they can be easily pierced with a fork, 12-15 minutes.
While the potatoes cook, heat 1 Tablespoon of the plant-based butter in a small skillet over medium heat. When hot, add the garlic. Stir until fragrant and tender, 5-6 minutes (see note). Turn off the heat and set the garlic butter mixture aside.
When the potatoes are cooked, drain the water from the pot. Combine the potatoes and other ingredients, including the butter garlic mixture but excluding the chives, in the pot.
Turn to medium-low heat. Mash and combine everything together. Continue to mash slowly as the mixture heats up and the potatoes reach the desired consistency. It took about 6 minutes for the potatoes to thicken to the way I like them.