Start by adding white chocolate chips to a glass or heat-proof bowl. Microwave the heavy cream for 1.5 minutes (be sure to place it in a large glass measuring cup or heat-safe bowl so that it has room to expand upwards). Pour the hot cream over the white chocolate chips but don't stir. Allow to sit for about 1 minute, then use a fork to stir; it will be thick and will likely look like it's going to mix together but keep at it for at least 30 seconds. At this point, the mixture will likely be thick and look a little grainy. Microwave in 15-second increments on 50% power, stirring in between each until smooth and pourable (I did four rounds of this).