1. In a jar or pitcher, combine the ground coffee and cold water, stirring to ensure all grounds are wet; cover and let it steep in the fridge for 12-18 hours.
2. Strain the mixture through a fine mesh sieve or coffee filter into a clean container, discarding the grounds—this is your cold brew concentrate.
3. In a glass, mix the coconut milk, vanilla extract, and simple syrup, stirring well.
4. Fill the glass with ice, pour in 3/4 cup of the cold brew concentrate, top with the coconut-vanilla mixture, stir gently, and garnish with toasted coconut flakes if desired.
