Dissolve the brown sugar. In a saucepan over medium-high heat, add the dark brown sugar and water. Stir them with a whisk as the sugar dissolves.
Allow it to thicken. Remove the saucepan from the heat and let the syrup thicken and cool to room temperature before using.
Cook the tapioca pearls. Bring a pot of water to a boil and cook the tapioca pearls according to the package. Then use a slotted spoon to transfer the cooked boba to a bowl. Mix in 1 tablespoon of dark brown sugar, which will dissolve as the boba cools.
Assemble your boba. Now in a 16 oz cup or glass, add 1/4 cup of the brown sugar syrup, 1/4 cup cooked boba, then a cup of ice. Now pour in a cup of milk with 2 Tbsp of heavy cream. Stir well and enjoy using a boba straw!