In a large bowl, whisk together the sweetened condensed milk, sour cream, cinnamon, nutmeg, salt, vanilla, and bourbon, until smooth.
Use an electric mixer to whip the cream until soft peaks that hold their shape form.
Fold half the whipped cream into the milk mixture, until combined, then fold in the rest of the whipped cream.
Transfer the ice cream to a lidded container and freeze for 8 hours, or overnight, until firm and scoopable.
Notes
Although the bourbon is optional, it helps make the ice cream more smooth and creamy.It's important to note that cinnamon is mainly fiber, so it does not "dissolve" into the ice cream. Since there's a lot of ground cinnamon in this ice cream, the texture can be noticeable. When the ice cream is super hard from the freezer, it may seem like the texture isn't very smooth, but this is just due to the cinnamon. It greatly helps to let the ice cream soften for 10-15 minutes before scooping it.