Preheat the oven to 400 degrees F.
Prick holes in the potatoes with a fork and place directly on the oven rack. Roast until cooked through, about 45 minutes, depending on the size of the potato.
While the potatoes are cooking prepare the crab: Add 2 tablespoons of butter to a frying pan. Add the shallots and cook until translucent. Next add the minced garlic and saute in the frying pan to gently brown the shallots and garlic. Add the thyme and crab and cook until heated through. Then set aside.
Lower the oven to 350 degrees F.
Once the potatoes are cooked and cool enough to handle cut, off a small portion of the top making an opening in the potato.
Take a spoon and scoop the pulp into a bowl. Place the potato skins on a cookie sheet and put in a 350 degree F oven for about 5 minutes to dry them out and ensure they will be crispy when done.
To the potato pulp, add the shallot/crab mixture, remaining butter, cheese and sour cream and mix. Then add parsley, salt and pepper, to taste. Fill the potato shells with the potato/crab mixture. Bake until cheese has melted around 35 to 45 minutes.
Sprinkle with parsley.