Preheat the oven to 400°F;
Gently scrub and dry the sweet potatoes, wrap tightly in aluminum foil;
Bake in the oven for about 1 hour, depending on the size of your sweet potatoes, bigger ones will take longer and vice versa;
Gently press on the sweet potatoes wearing oven gloves, if it's soft to touch then it's done;
Peel and scoop out the sweet potato flesh, be careful not to burn your hands! Transfer to a big bowl and mash with a fork till smooth and creamy, sweet potatoes have different levels of moisture so if it's too dry, add a small splash of soy milk;
Pick a mold that you like, fill the mashed purple sweet potatoes in it and press firmly, smooth out the top;
Lift up the mold to release the sweet potato tower, once it's chilled, add on yogurt drizzle, garnish with mint, enjoy!