Prepare an ice bath by placing a glass or metal bowl in a large bowl of ice.  Add the heavy cream to the bowl and set a fine-mesh sieve over the bowl.

In a small mixing bowl, whisk together the egg yolks, granulated sugar (2 Tablespoons) and the salt.  Whisk until the yolks are a little foamy and pale.

In a medium saucepan stir the milk and brown sugar together.  Heat over medium-high until it comes to a rolling boil.  This milk and sugar mixture may look curdled but this is normal.  Remove from the pan from the heat.

While whisking the yolk mixture constantly, gradually add the hot milk mixture in a small stream until it is completely blended.  Pour the now combined yolk, milk and sugar mixture back into the saucepan.

Return the saucepan to the stove and heat over low until the mixture is thick enough to coat the back of a spoon. This should only take a few minutes.

Immediately strain the mixture into the glass bowl with the heavy cream in it.  If the mixture is not completely smooth you may use an immersion blender to get the lumps out.

Allow the custard to cool completely, stirring occasionally.  Add the vanilla and bourbon if desired.  Cover and chill overnight.  Process according to your ice cream manufacturing directions and freeze in an airtight container until frozen.