In a Dutch oven or large stock pot, sauté sliced onions with garlic and butter slowly on medium stirring often, and cooking for about 10 minutes. Then let the onions caramelize and only story every few minutes for at least another 50 mins or up to 3 hours until caramelized. Be sure that the onions do not burn, but a little sticking to the pan is what will help develop the brown color. If they’re sticking too much, add a tablespoon of water. To quicken the caramelization, you can add a teaspoon of sugar.