For the cinnamon sauce in a small saucepan over medium heat combine the brown sugar, the flour and 180ml hot water, cook until uniform, add the butter and 3/4tsp cinnamon powder, cook until thickened and smooth. Cool and store in an airtight container until ready to use.
Dissolve the cornstarch in 50ml whole milk, leave to rest.
For the ice cream in a small saucepan over medium heat combine the heavy cream, the leftover milk, white sugar, pinch salt, the vanilla bean seeds, crushed cinnamon sticks and 1/2tsp cinnamon powder, stir, bring to an almost boil, take off heat and leave to steep covered for 1 hour. Strain the mixture, discarding the vanilla bean and the cinnamon sticks, return to medium heat, bring to an almost boil, add the cornstarch milk and cook stirring constantly until thickened. Take off heat, add the cream cheese, stir until creamy and smooth. Cool to room temperature and transfer to the fridge overnight.
Freeze in your ice cream maker according to the manufacturer's instructions adding small bites of 1/2 Cinnabon Classic Roll at the last couple of minutes of churning. Spoon into an airtight container alternating layers of ice cream and the cinnamon sauce, store in the fridge for at least 5 hours until set.