Scrub potatoes and pierce with all over with a fork. Place in microwave on high power setting for 7 minutes or until flesh is tender when pierced. Remove from microwave.
In a nonstick skillet cook onion in 1 tbsp of butter, until soft and translucent. Set aside. In same skillet add pepperoni and cook until crisp.
Cut potatoes lengthwise in half. Scoop out flesh, leaving a ¼ inch border, into a large bowl.
Rice or mash potatoes. Add sour cream, ½ cup of the Cheddar cheese, remaining butter, cauliflower, pizza sauce and chopped pepperoni. Season with salt and pepper. Combine ingredients.
Spoon mixture into potato skins. Top with remaining Cheddar cheese and pepperoni slices.
Microwave for 3 minutes, or until heated through.