2In a large, heavy-bottomed pot or Dutch oven, melt the Unsalted butter with the Extra-virgin olive oil over medium-low heat. Add the sliced Yellow onions, Fine sea salt, and Black pepper. Cook very slowly, stirring occasionally, for 60-90 minutes, until the Yellow onions are deeply caramelized to a rich golden-brown color. This process should not be rushed.
3Add the minced Garlic cloves, Bay leaf, and Fresh thyme to the pot. Cook for another 5 minutes, stirring, until the Garlic cloves are fragrant.
