I want to make dulce de leche by boiling it. As the store bought cans leach plastics like BPA into the food, I want to avoid using it.   What are jars/cans, preferably reusable that you can put inside some food, close it and boil for several hours and are made from safe for humans material? 
Is the meat cooked or not ? it's not clear.  I would prepare the stuffing, cook it all and cool it down and stuff the cannelloni and put that in the fridge.  Personally, I would bake it all, sauce included the day before and cool it down and put that in the fridge. (I treat that the same as a lasagna). 