Rinse 1 cup of small tapioca pearls under cold water in a fine mesh strainer until water runs clear, about 2 minutes. This removes excess starch and prevents clumping.

In a medium saucepan, combine the rinsed tapioca pearls with 3 cups of coconut milk and 1 cup of regular milk. Add a pinch of salt and stir well to combine.

Place the saucepan over medium heat and bring the mixture to a gentle simmer, stirring frequently to prevent the tapioca from sticking to the bottom. This should take about 8-10 minutes.

Once simmering, reduce heat to low and continue cooking for 20-25 minutes, stirring every 3-4 minutes. The tapioca pearls will gradually become translucent and the mixture will thicken.

When the tapioca pearls are mostly translucent with just a small white dot in the center, add 1 can (14 oz) of sweetened condensed milk and 1 teaspoon of vanilla extract. Stir continuously for 3-4 minutes until well incorporated.

Remove from heat and stir in 2 tablespoons of butter until melted and fully combined. The mixture will be thick but will set further as it cools.

Pour the tapioca mixture into a large serving bowl or individual ramekins. Let cool at room temperature for 15 minutes, then cover with plastic wrap pressed directly onto the surface to prevent a skin from forming.

Refrigerate for at least 3 hours or overnight until completely chilled and set. Before serving, garnish with toasted coconut flakes and a light dusting of cinnamon if desired.