For the panna cotta: Combine 1 can evaporated milk with four packages gelatin in a medium mixing bowl and bloom for 5 minutes.
Put the remaining 2 cans evaporated milk, the cream, sugar, vanilla bean, salt, and bourbon, if using, in a 3-quart saucier and bring to a bare simmer over medium heat. As soon as you see bubbles in the mixture, pour it into the gelatin mixture and stir until all the solids have dissolved. Let cool at room temperature for 1 hour. Pour through a strainer into a 6-cup brain mold. Refrigerate overnight to fully set.
For the glaze: Combine remaining package of gelatin with 1/2 cup of the cranberry juice in a small bowl and let bloom for 10 minutes.
Put the remaining 1 1/2 cups cranberry juice in a 2-quart saucepan and bring to a boil. Remove from the heat and pour into the gelatin mixture, stirring to dissolve the solids. Transfer to a squeeze bottle and leave at room temperature until the panna cotta brain is set.
Unmold the panna cotta and drizzle the glaze over it. The glaze will set up immediately. Serve chilled.