Prepare your dish for the milk tart by arranging the biscuits at the bottom and on the sides of the dish.
Beat the eggs and sugar until fluffy and light.
Make a mixture in a cup with the corn flour, flour, custard powder, salt and vanilla with a little of the milk so as to not form lumps.
Pour milk and the butter in saucepan and bring to boil. Be careful not to burn the milk.
Add the corn flour mixture and lastly the eggs and sugar.
Place back on extremely low heat and constantly mix with a whisk while you let it simmer for at least 10 minutes until thickened and completely cooked. Be careful to not let it burn. If not thick enough, add a tablespoon of corn flour mixed with a little milk.
Keep whisking until the sauce is blended and smooth.
Simmer for another three to four minutes, whisking frequently. The mixture should have the consistency of a thick sauce.
Pour in prepared dish. Sprinkle with cinnamon sugar.
When cool, place in refrigerator for 1 hour or longer.