In a large pot, cover Creamer potatoes with a generous amount of cold water and bring to a boil. Boil for 15 minutes (or until tender.)Preheat oven to 375F.While the potatoes are boiling, heat olive oil in a large skillet over medium-high heat. Add the onion, celery, carrots, garlic, and kale. Sauté for 2 minutes. Add the mushrooms and thyme. Continue sautéing until the vegetables are nearly tender.Evenly sprinkle the flour over the vegetables and stir to coat. Cook for 1 minute. Gradually and in small amounts, add the veggie broth to the vegetables using a whisk to incorporate the broth. Keep adding more broth until the consistency is a thin gravy. Add the corn, peas, and lentils. Simmer for 5 minutes (add more water if needed.) Pour veggie mixture into a large casserole dish. Spoon or pipe mashed potatoes evenly on top. Cover the casserole dish with a lid or foil and bake for 25 minutes. Remove the lid and broil for 2-5 minute until browned to your liking.