In a large skillet, heat 1 tablespoon of olive oil over medium heat. Add the gnocchi in batches, ensuring they don’t overcrowd the pan. Sauté them for 3 to 5 minutes until they turn golden-brown on the outside, gently flipping for even cooking.

In the same skillet, melt 2 tablespoons of unsalted butter over medium heat. Add thinly sliced yellow onions along with half of the thyme, kosher salt, and black pepper. Cook the onions for about 30 minutes, stirring occasionally until deeply caramelized.

Pour in half a cup of dry white wine while scraping the bottom of the skillet to deglaze. Allow the wine to simmer and cook down for around 1 minute.

Stir in 1 tablespoon of balsamic vinegar, then return the cooked gnocchi to the skillet and toss everything together.

Sprinkle Gruyere cheese over the gnocchi and onion mixture. Reduce heat to low, allowing the cheese to melt for about 2 minutes, then broil for 4 to 6 minutes until bubbly and golden brown.

Remove from the oven, sprinkle remaining thyme and black pepper, and serve immediately.