Whisk together eggs and water until well combined. Then add in the cornstarch and whisk until well combined.
4 large eggs, 45 ml water, 60 grams cornstarch
Place the milk, condensed milk, vanilla and cinnamon sticks in a medium-sized pot. Bring to a boil, whisking occasionally to make sure the condensed milk has fully dissolved. Once the milk has come to a boil, turn down the heat to low and remove the cinnamon sticks.
720 grams milk, 395 grams sweetened condensed milk, 1 tablespoon vanilla extract, 2 cinnamon sticks, 1 teaspoon table salt
Rewhisk the egg mixture. Then slowly, while continuously whisking pour the egg mixture into the milk mixture. Whisk continuously while cooking the filling until it is thick, and the whisk is leaving a very distinct line in the filling. This will take between 5 and 15 minutes. Remove from the heat.
Allow the milk to cool for about 5 minutes whisking occasionally and then pour into the prepared biscuit base. If using loose biscuits, they may move around a bit during the process. Just use a fork to gently prod them back into place.
Cover the top of the filling with cling film or plastic wrap and allow it to cool until lukewarm at room temperature. Place in the fridge and allow to sit for at least 4 hours, preferably overnight.
Gently remove the cling film and sprinkle with about 1 tablespoon of cinnamon. Slice, serve and enjoy.
1 tablespoon ground cinnamon