Bring the water to the boil and steep the teabags for 5 to 10 minutes until you have a strong brew. Allow the tea to cool for at least 10 minutes.
Place 1 cup of the tea, the condensed milk and the whipping cream in a blender and whisk to combine. Continue whisking until the mixture is thick.
Pour into a baking tin or other freezer-proof container and freeze for at least 2 hours. Remove after one hour and give the mixture a good stir. Return to the freezer. Remove again after another hour and stir again.
For the caramel
Add white sugar and ¼ cup of the tea to a medium saucepan and heat over medium heat, stirring constantly until the sugar is completely dissolved and melted and the mixture thickens. Mine was paler, frothy and syrupy. Be careful not to burn the sugar or yourself.
Add the butter, stirring as you do. Be careful as the mixture will bubble rapidly and can burn. Continue to stir for about 2 minutes or until the butter has completely melted.
Remove from the heat and add the double cream to the mix, stirring continuously. Once the mixture is smooth, return it to the stove and bring the mixture to the boil. Allow it to boil for 1 minute. Keep an eye on it and remove it from the heat and stir if it threatens to bubble over.
Remove from the heat, add salt and stir well. Allow to cool down before using and tasting else you will burn your tongue!
When the caramel has completely cooled, remove the ice cream from the freezer. Drizzle the caramel over the top and swirl through.
Return to the freezer to freeze for a further hour before serving.
If you want the ice cream to be caramel as well, add caramel condensed milk or a jar of caramel spread (such as Bon Maman) to the blender instead of the condensed milk.You can make the caramel sauce in advance. It will (normally) keep for a day out of the refrigerator. Otherwise, cover well and refrigerate it for up to a month. Remove it from the fridge and allow it to reach room temperature before using.If your butter separates when you add it to the sugar and tea, remove the saucepan from the heat and whisk quickly to combine again.