For the salted caramel
Put sugar in a small, high pot and distribute evenly on the base. Melt over medium-low heat with a lot of patience without mixing. At most, you can delicately push the already caramelized part towards the still white sugar without touching it with the spatula. As soon as the sugar is completely caramelized and amber (if you have a thermometer you can heat it to 170-175 degrees but make sure the temperature doesn’t exceed 175 degrees!), lower the temperature to a minimum and add cold butter in cubes. Mix well until the butter is completely melted and you get a homogeneous mixture.