The framework of this leftover recipe for vegetable chowder is quite flexible. I used a 1 to 1 ratio of leftover vegetable to leftover mashed potatoes but you could easily increase or decrease that ratio depending on how chunky you like your soup.
If you need to reheat the vegetable chowder, I recommend adding more broth or milk as needed. The starch of the mashed potatoes acts as a thickener and you will need more liquid to achieve a soup-like consistency when reheating.
I use Pacific Foods brand oat milk instead of milk or cream in this leftover vegetable chowder recipe to keep the recipe vegan. Oat milk has a more savory quality compared to almond or cashew milk. You can use other nut milks but be sure to select an unsweetened variety.
If you have leftover turkey, you can add it to the vegetable chowder when you add the cooked vegetables.
I used carrots, green beans, and mushrooms for this recipe to mimic traditional Thanksgiving leftovers such as green bean casserole. You could easily use whatever leftover or fresh vegetables you have in your fridge such as celery, cauliflower, parsnips, or broccoli.