Bring a large pot of water to a boil. Meanwhile, cut potatoes into 1-inch cubes, leaving the skin on (optional). Add potatoes to the boiling water, cover and cook until fork tender, about 8 minutes. Drain potatoes and return to the pot. Add a splash of plant-based milk and spices. Using an electric mixer, whip the potatoes until fluffy. Add additional plant-based milk as necessary to achieve desired consistency. Taste, adding more garlic, onion, plus salt and pepper as desired.