½ cup dry sherry, vermouth, or white wine (optional; sub with an extra ½ cup of beef broth if not using)
2½ cups low-sodium beef broth
2 cups cooked chicken, shredded or diced (I used a store-bought rotisserie chicken for this)
1 (17-oz) package shelf-stable potato gnocchi
1½ cups grated gruyere cheese
½ cup grated parmesan cheese
1 cup panko breadcrumbs
Salt and pepper, to taste
Fresh thyme leaves, for garnish
Preheat the oven to 425°F.
Place a large ovenproof skillet or braising pan over medium heat and add the butter. Once it is melted, add the onions and a pinch of salt and cook, stirring frequently, for about 5 minutes.
Add in the garlic, thyme, and sugar and stir to combine. Cook over medium-low heat for 25-30 minutes, stirring frequently, or until the onions are soft and deeply golden brown.
Sprinkle the flour over the onions and stir to coat. Cook for a minute so the raw flour taste disappears and then slowly stream in the sherry/vermouth/wine, scraping up any brown bits that may have formed on the bottom and sides of the pan.
Cook for a couple minutes and then slowly stream in the beef broth. Bring the mixture up to a simmer and cook, stirring constantly, until the broth thickens up a bit. Season, to taste, with salt and pepper.
Add in the cooked chicken and gnocchi and stir to combine.
Top everything with the grated cheeses and the breadcrumbs. Transfer the pan to the oven and cook for 20 minutes, or until the top is bubbly and golden in spots.
Serve hot and garnished with additional thyme leaves.