Preheat the oven to 250 and set the chopped white chocolate on a very clean, large cake pan.

Let it toast for a total of 45 minutes, stirring with a rubber spatula (ensuring that you scrape it up from the bottom and the corners to get an even toast) every 10 minutes. The chocolate will melt first, then it will get stiffer and stiffer as it caramelizes and at some point toward the end it will smooth out again. Once it gets to a point where the color doesn’t change much when you scrape it, it’s done.

Pour it into a food processor and process it until it’s smooth.

If you are moving straight to making the ice cream, measure out 15 oz of the melted chocolate. If you have any left, spread it onto a sheet of parchment paper and let it solidify. You can break it up and use it in something else later.

If you aren’t making the ice cream straight away, pour all the melted chocolate in a pan lined with parchment paper. Let it solidify (will take at least a few hours, usually overnight) and then break or chop it up and store in an airtight container.

If your 15 oz of caramelized white chocolate is solid, heat it in the microwave - stopping when it’s mostly melted and stirring until smooth.

Warm 1 cup of the heavy cream until it’s warm to the touch. Pour it into the melted chocolate and stir until you have a smooth ganache. Let it cool slightly (we don’t want to add whipped cream to hot ganache or it will melt it).

Whip the remaining 1 ½ cups heavy cream and salt and vanilla in a stand mixer or with a hand mixer until you have medium-stiff peaks (they should mostly hold shape).

With a rubber spatula, fold the whipped cream into the ganache. You will have a very runny mixture. Pour it into a loaf pan, cover it with plastic wrap and set it in the freezer overnight. If it's gone very hard, give it 10 minutes at room temperature before scooping.