Kosher salt and freshly ground black pepper, to taste
PREPARATION
Preheat oven to 375°F.
In a large skillet over medium-high heat, melt butter. Add onions and season with salt and pepper and thyme. Cook slowly until very soft and caramel colored, stirring occasionally.
Deglaze pan with sherry or wine, then add stock and bring to a low boil. Let cook until liquid is nearly gone, 5-10 minutes.
Meanwhile, cut the top third off of each potato and scoop the flesh into a medium bowl. Add half of the onion mixture to the potato flesh and stir to combine.
Refill each potato shell and place on a baking sheet. Top with remaining onions and gruyere cheese.
Bake until cheese has melted. For more color, broil on high for 1 minute. Enjoy!