Preheat oven to 375°F.

Heat a skillet over medium-high heat. Add the butter and melt, then add the sliced onions. Cook for a few minutes until soft and translucent. Season with salt, pepper, and sugar. Continue to cook, stirring frequently, until the onions are caramelized. Remove from heat and allow to cool slightly.

Heat the cream in a small sauce pot with the dried bay leaves, garlic cloves and thyme sprigs, over low heat. Do not bring to a boil, it should just barely simmer and heat through for about 5 minutes. Remove from heat and set aside.

Using a medium, deep baking dish, layer the sliced potatoes to completely cover the bottom. Top with some of the caramelized onions, and ladle a bit of the warm cream over. Sprinkle with grated Romano cheese and repeat the steps until all the onions, cream and potatoes are used. Make sure to finish off with a layer of potatoes. Using a spatula, press down on the potatoes to allow the cream to rise to the surface. Sprinkle with remaining Romano cheese and gruyere cheese. Add a bit of freshly cracked black pepper if desired. Bake for about 35 to 40 minutes or until the potatoes are tender, the cream is bubbling and the cheese on top is browned.

Remove from oven and allow to set for about 20 minutes before serving. Sprinkle with chopped chives and parsley for garnish. Enjoy!