In a clean jar or container with a lid, add milk, heavy cream and Earl Grey tea (bags or loose tea leaves). Close the lid shut and let it cold brew in the fridge for 8 to 24 hours.
Remove Earl Grey tea bags, or, if using loose tea, pour the cream through a fine mesh strainer to remove the leaves.
In a pot or pan, over low heat, heat the Earl Grey milk cream mixture until warm-hot. Do not boil. Let it cool for 5 minutes.
While cream cools, in a small bowl, mix cornstarch with 3 tablespoon of milk. I don’t mix it directly into the egg mixture to avoid clumps.
In a bowl, whisk room temperature egg yolks, sugar and vanilla or Earl Grey extract until well combined.
Add the diluted cornstarch and whisk to combine.
Place the pot back over low heat and slowly add the egg mixture. Whisk until thickened. It will have a silky texture when ready.
Cover with plastic film, and let it cool at room temperature. After cooled, you can use it or store it in the fridge for up to 5 days.