In a m medium saucepan, combine the milk, heavy cream, and condensed milk. Stir until the condensed has been completely incorporated into the milk and heavy cream. Add the cinnamon sticks and vanilla powder. Bring the mixture to a simmer over high heat. Once the mixture has simmered, turn off the heat and allow to steep for 45 minutes to 1 hour. As the mixture steeps, separate the egg yolks and place in a large bowl.
Add ice water to a bowl large enough to hold ice water and bowl with the egg yolks.The cinnamon mixture should be properly steeped and cooled by now. Remove and discard the cinnamon sticks from the cinnamon mixture and pour it over the egg yolks, whisking all the while until completely incorporated. Pour the custard in a medium saucepan (use the same pan you used to steep the cinnamon mixture). Cook the custard over medium/low heat, stirring the ENTIRE TIME until the mixture coats the back of a wooden spoon thickly.
Pour the mixture into the bowl you used for the egg yolks and nestle it in between the bowl of ice water. Add the Vietnamese and Chinese cinnamon and whisk until the cinnamon is completely mixed in and there are no visible clumps of cinnamon powder. Stir the mixture occasionally until completed cooled.
Once cooled place the custard in an airtight container and store in the fridge for about 4 hours or overnight to steep and deepen the flavor. Freeze according to your ice cream maker directions.
If you wish, you can freeze the custard right away. It's cool. I refer to steep for a bit prior to freezing.
Once the ice cream has frozen, pour about 1/3 of the ice cream in desired vessel (I used a loaf pan). Add 6-9 (or 9-12) small scoops of dulce de leche and pour another layer of ice cream, followed by 6-9 (or 9-12) small scoops of dulce de leche. Add the remaining ice cream and if desired, add more scoops of dulce de leche. Cover and place in the freezer for about 4-5 hours until completely frozen.