Line a muffin pan with 6 cupcake liners (or around 12 mini cupcake liners)
Melt the white chocolate in the top of a double boiler or in a microwave. Once it’s melted, whisk in matcha powder until combined. Pour about a 1 tablespoon of the melted white chocolate into each muffin liner. You will want to use half of the melted chocolate so the remaining can be used to cover the top. Tap the muffin pan so the chocolate settles. Transfer to the freezer for 5 minutes to set.
Meanwhile, make the coconut filling. Combine heavy cream, salt and sugar in a saucepan over a low medium heat. Whisk until sugar is dissolved. Add in shredded coconuts, marshmallow and vanilla extract and keep stirring until marshmallow has melted and the texture has thick consistency. Remove from heat and let it cool before using.
Once the chocolate has set, add 1 tablespoon of coconut filling and press it gently into the chocolate layer that has been set, then spoon additional chocolate on top until all of the coconut filling is completely covered in chocolate. Repeat until all prepared cupcake liners have been filled.
Allow all the cups to sit until the chocolate has set at room temperature or (this may take an hour), or you can speed up the process by placing the cups in the fridge for at least 30 minutes.