Using a large saucepan on medium heat, combine the remaining 1 ¾ cups milk, cream, dark brown sugar, granulated sugar and vanilla. Whiskt he ingredients together to combine and continue to slowly whisk to prevent a skin forming as the sugar melts.
Reduce the heat to a simmer and continue to stir for 4 minutes.
Spoon about ¼ cup of the hot mixture int the bowl of the cornstarch slurry. Then, pour the slurry into the saucepan.
Turn the heat back up to medium and cook the base, continuing to whisk until it reaches a boil. Boil this mixture for 1 minute then remove pan from the heat.
Add in the cream cheese mixture stirring until smooth.
Pour in the ½ cup of Saint Brendan's Irish Cream and stir in the mashed half of brûlée bananas.
Transfer base to a large bowl, cover with plastic wrap and refrigerate for 3-4 hours until cold. (or overnight if needed)