Preheat oven to 350ºF. Lightly oil a 9-inch by 13-inch casserole dish. Bring a large pot of water plus 1 tablespoon of salt to boil. Add cauliflower and cook for about 3 minutes, until it's tender. Use a slotted spoon to transfer to a bowl then lightly mash with a fork. Use the same water to cook the bowties according to package instructions. Drain and transfer to a separate bowl.

Heat the oil in a pan over medium heat. Add the onion and 1/2 teaspoon of salt and the pepper. Cook, stirring occasionally, for about 8 minutes until onions are translucent and very soft, without browning. Add garlic and cook for another 2 minutes until it becomes fragrant. Remove from heat and set aside.

Crumble the tofu into small "curd" in a large bowl. Add nutritional yeast, onion powder, remaining 1/2 teaspoon of salt, and lemon juice. Mix well. Stir in sour cream, mashed cauliflower, and the cooked onions and garlic. Add in the bowties and stir to combine. Taste and adjust seasonings by adding more salt and ground black pepper, if necessary. Empty contents of the bowl into the prepared casserole dish and bake for about 25 minutes, until the tops of noodles begin to brown and get crispy. Remove from the oven and serve immediately.