Wash and scrub your potatoes. Then dry and lightly coat with oil. Place directly on the top or middle rack and bake for 1 hour, 15 minutes, or until they’re golden brown and have a bit of “give” to them when lightly squeezed.
Remove from oven and let cool until they’re comfortable to handle.
In the meantime, steam your cauliflower over a double boiler (or in the microwave) for about 15 minutes or until tender.
When your potatoes are cooled, cut them in half and gently scoop out the insides with a spoon, leaving about a 1/4 inch rim. Add the potato and steamed cauliflower to a large mixing bowl, along with the butter, garlic powder, salt, pepper, and sour cream and combine with either a potato masher or hand-held mixer. Be careful not to overmix or the potatoes can become sticky. Add a splash of milk if it appears too thick.
Preheat oven to 350 degrees F (176 C).
Scoop the filling back into your potatoes and place in a baking dish. Top with a sprinkle of cheddar cheese (optional) and bake for 15 minutes, or until the cheese is melted and the potatoes are warmed through.
Serve immediately, topping with chives or green onion (optional). Cover and store in the fridge for up to a few days.