Heat a saucepan over low-medium heat.
Add coconut milk and sugar and bring to a simmer.
Meanwhile, whisk eggs and add in arrowroot powder.
Pour one ladle of the steaming milk into the egg mixture, whisking constantly.
Turn the pot of coconut milk to low and add the egg mixture and continue whisking until thickened.
Once it thickens, remove from heat and stir in vanilla and butter.
Pour 2 ounces (1/4 cup) into each mason jar; cool until well chilled.
Pre-heat a non-stick griddle or pan to 450 degrees F.
Add mango planks and cook until lightly caramelized on each wide side, 2 to 8 minutes, depending on the thickness of the plank and ripeness level of the mango.
Cool on a rack until cool enough to handle; dice 3/8-inch.
On top of chilled coconut cream layer: 1 ounce oatmeal cookie crumble, 2 ounces caramelized mango and a pinch of toasted coconut.
Source: Chef Dave Woolley