Combine 1 can of evaporated milk with four packages gelatin and bloom for five minutes.
In a heavy-bottomed saucepan, bring the remaining milk and heavy cream to a boil. Stir in the sugar, vanilla bean, salt, and bourbon (optional). Combine this mixture with the gelatin mixture and stir until all solids have dissolved. Remove the vanilla bean and pour the mixture into a six-cup brain mold. Refrigerate overnight to fully set.
For the glaze, combine remaining gelatin with half a cup of cranberry juice. Bring remaining 1 1/2 cups of juice to a boil and stir into gelatin mixture to dissolve any solids. Pour into a squeeze bottle and leave at room temperature until panna cotta brain is set.
Unmold the panna cotta and drizzle the glaze over it. The glaze will set up immediately.