2 onions, thinly sliced
1 tablespoon (15 ml) butter
1 teaspoon (5 ml) brown sugar
1/2 teaspoon salt
6 Russet or Yukon Gold potatoes, thinly sliced
1 tablespoon (15 ml) fresh thyme, chopped
3 cloves garlic, minced
1 cup (250 ml) whipping cream
1/2 cup (125 ml) chicken or vegetable broth
1 cup (250 ml) Parmesan cheese, grated
Salt, to taste
White pepper, to taste
Place the onions, butter, brown sugar, and salt in the bottom of a 6-quart slow cooker, mixing to combine. Cover and cook on High for 30 minutes. Turn slow cooker off, remove onions, and set aside.
In a large bowl thoroughly combine the potato slices, thyme, garlic, and a pinch of salt and white pepper to taste.
In a small bowl, whisk together the whipping cream and broth.
Lightly oil the slow cooker and add half of the potatoes, and half of the caramelized onions. Sprinkle the potatoes with 1/4 cup (60 ml) of the Parmesan cheese and over that, pour 1/2 of the cream and broth mixture. Top with remaining potatoes and onions, and continue with the layers of adding 1/4 cup (60 ml) of the cheese, and pouring the remaining cream mixture over top.
Cover, set to high and cook for 4 hours and 30 minutes, or until the potatoes are tender throughout.
At the end of cooking time, sprinkle potatoes with remaining 1/2 cup (125 ml) of the Parmesan, cover and set to low. Continue to cook for another 15 to 20 minutes, until the cheese is completely melted.