Seizing happens when the melted sugar recrystallizes on the sides of the pot or isn’t fully dissolved before it starts boiling, and the sugar mixture turns grainy instead of smooth and liquidy. If your caramel seizes, simply add ½ cup of water before adding butter or cream, and heat the water and sugar over medium heat, stirring the mixture occasionally to clean the crystals off of the side of the pot, or until the sugar has dissolved in the water. Bring the water and sugar solution to a simmer, cooking it until it is the deep amber color and brushing any sugar crystals off the side of the pot with a damp pastry brush. As the solution simmers, the extra water will evaporate. The cooking time will be longer given the added water. Once the caramel is amber, continue with the rest of the recipe as directed.