Steep mint in hot cream: Bruise the leaves with a wooden spoon so they'll release their essential oils and flavors.
Place them in a saucepan with the milk and 3/4 cup of the cream. Bring just to a simmer, then remove from heat and cover to steep for 30 minutes.
Prepare sieve over bowl with cream, over ice bath: Fill a large bowl with ice water and set another bowl with the remaining cream in it with a fine mesh sieve over the cream. In a separate bowl whisk together the egg yolks.
Strain mint cream, add sugar, salt, then heat until steamy:
Pour the steeped cream mixture through a strainer and toss the mint leaves. Return the milk/cream mixture to the saucepan and add the sugar and salt. Set over medium heat and heat until steaming (not boiling).
Temper eggs, return to milk mixture: Slowly pour some of the heated milk mixture into the egg yolks, whisking constantly so that the egg yolks are tempered by the heated milk, but not cooked by it.
Pour the egg yolk mixture back into the saucepan.
Heat until thickened: Stir the mixture over medium heat with a wooden spoon, constantly scraping the bottom of the pan as you stir. When the mixture thickens up and coats the back of the spoon so that you can run your finger across the coating and have the coating not run. This can take between 3 and 10 minutes depending on the heat of your burner.
Strain through sieve, add bourbon and vanilla, chill:
Pour the mixture through the sieve into the chilled bowl of cream.
Mix in the bourbon and vanilla. Cover and place in the refrigerator until the mixture is chilled, 6 hours to overnight.
Process in ice cream maker: Process in an ice cream machine per the manufacturer's instructions.
Store in freezer: Store ice cream in an airtight contained in the freezer for several hours before serving to harden the mixture up a bit. The ice cream will be quite soft straight out of the ice cream machine and will need to harden up a bit for proper ice cream consistency. If you leave it in the freezer too long, just let it sit a few minutes before serving.
*Note: You cannot substitute anything for the bourbon in this recipe. Otherwise, it's not a mint julep. That said, you can make a simple mint ice cream, if you don't want to use alcohol. Check out the mint chocolate chip recipe on the site.
