1. Preheat the oven to 375 F.
2. Scrub the potatoes and pat dry.
3. Place the potatoes on a foil or parchment lined baking sheet.
   
4. Place in oven and bake for one hour or until you can easily run a fork through the potatoes.

Make the Fondue:

1. In a separate small bowl, whisk together the cornstarch and lemon juice.
2. Place the shallots in a fondue pot or heavy bottomed saucepan
3. Add the champagne or wine and bring to a boil over medium heat. Let simmer for 2 minutes.
4. Remove the pot from the heat and stir in all the cheeses. Mix in the cornstarch/lemon mixture.
5. Return the pot to medium heat and cook, stirring until everything is melted and smooth.
6. Season with nutmeg and white pepper.
7. Cover and keep warm.
8. Remove the potatoes from the oven.
9. when the potatoes are cool enough to handle. Cut a large oval lengthwise in the top.

Assemble the Fondue Potatoes

1. Use a teaspoon to hollow out the potatoes, leaving about 1/4 inch of potato flesh all around in each.
   
2. Spoon the fondue into each hollowed out potato. You may need to slightly reheat the fondue.
   
3. Return them to the top rack oven heated at 350 degrees F.
4. Bake for 10-15 minutes until the cheese starts to bubble and is slightly brown at the edges.
   
5. Remove from oven. Plate and serve.