Pre heat the oven to 375 degrees.

Prick the russet potatoes with a fork and cook in the microwave until the potatoes are very soft and a knife can easily slide into them.

Remove the potatoes from the microwave. Scoop out the flesh and using a ricer, squeeze the potatoes into a mixing bowl. Add the softened butter, egg yolks, salt, pepper and nutmeg. Using a spatula stir the potatoes until all the ingredients are thoroughly combined.

Spoon the mixture into a piping bag with a star tip.

On a parchment lined baking sheet, pipe acircle about 3 inches in diameter. Pipe the potatoes to fill the circle and then pipe 3 layers on top of the circle to form a cup. Repeat with the remaining potato mixture. You should have 4 potato cups.

Mix the remaining egg with the water in a small bowl and with a pastry brush, lightly brush the cups with the egg wash.

Bake in a 375 degree oven for 10 - 12 minutes until the edges are golden and the potatoes have firmed.

Remove from the oven, fill with the potato and mushroom mixture and serve.

While the russet potatoes are cooking, bring a small saucepan of water to a boil. Add the Pee Wee potatoes and cook for 10 minutes until the potatoes are tender. Drain and rinse with cold water to stop the cooking. Set aside.

In a medium saute pan, melt the butter over medium heat. Add the shallots and mushrooms,salt, pepper and nutmeg. Cook until the shallots are very soft and the mushrooms and tender. Add the potatoes and cook for 5 minutes. Add the marsala and thyme and cook for 3 minutes or until almost all the liquid evaporates. Stir in the creme fraiche and stir until incorporated. Taste and adjust the seasonings. Add the parsley and stir. Divide the potato and mushroom mixture among the potato cups.