Wash the potatoes, poke them all over with a fork and pat dry.
Bake the potatoes at 400° for 50-55 minutes.
In a frying pan brown the sausage over medium high heat for about 10 minutes until cooked. Drain the fat and place the sausage meat in a medium bowl. Set aside.
Add the onions, garlic, green pepper, mushrooms and 1 Tablespoon butter to the frying pan. Cook on medium heat until tender, about 5-8 minutes. Add the tomato paste, Italian seasoning and parsley, stir to combine.
Add the vegetable mix to the bowl of meat mixture and mix well. Add a little bit of salt and pepper to taste. Set aside.
When the potatoes are done cut the top 1/3 off of the potato. Carefully scoop about 1/2 of the inside of the potato out while keeping the potato skin whole. Put the inside of the potato that you scoop out into a separate small bowl.
Add the ⅓ cup butter and 1/2 cup grated cheese to the potato that is in the bowl and mash well. Add the sausage mixture and stir to combine.
Fill the potato skins with as much filling as you can. sprinkle a little bit of cheddar cheese on top of each one. Place the potatoes back on a parchment paper lined baking sheet and bake at 400° for 10 minutes.
Serve immediately garnished with fresh parsley and a dollop of sour cream.