For the caramelized onions (can be made night before:) Add a small splash of olive oil, plus 4 tbsp of butter to a large deep skillet over medium heat. Add the onions. Let the onions cook for 30 minutes to 1 hour, stirring every few minutes. As soon as the onions start developing color, deglaze the pan with a splash of some chicken or beef stock. Continue to do this until they are uniform in deep caramel color and extremely thin and wilted. Transfer to a dish and allow to come to room temp before putting in the fridge.